We know Ned was opposed to killing Dany since he saw her as a child and not a threat but do you think he would he changed his mind if he had lived long enough to know she had dragons and was conquering cities? I saw an interview where the actor that plays Jon on the show said Ned would be disappointed on Jon for killing Dany and I can't help but disagree, I think Ned would be disappointed in Jon for bending the knee to a Targaryen in the first place
i haven't watched the show & in general i don't like to pay too much attention to what actors say of characters they play. i'm very hesitant to participate in celebrity/stan culture where effectively some dude's opinion is given influence over mine by virtue of them being famous. i only ever talk about asoiaf, it's supplemental materials, & the creator's informing thoughts on here cause that's all i feel confident in/informed enough to speak of
that said i'm also confused by your question a bit, the Ned would be disappointed in Jon for bending the knee to a Targaryen part seems a stretch. we can walk through how i approach it:
"DaenerysĀ TargaryenĀ has wed some Dothraki horselord. What of it? Shall we send her a wedding gift?"
"He would say that even a million Dothraki are no threat to the realm, so long as they remain on the other side of the narrow sea," Ned replied calmly. "The barbarians have no ships. They hate and fear the open sea."
The king shifted uncomfortably in his saddle. "Perhaps. There are ships to be had in the Free Cities, though. I tell you, Ned, I do not like this marriage. There are still those in the Seven Kingdoms who call me Usurper. Do you forget how many houses fought forĀ TargaryenĀ in the war? They bide their time for now, but give them half a chance, they will murder me in my bed, and my sons with me. If the beggar king crosses with a Dothraki horde at his back, the traitors will join him."
"He will not cross," Ned promised. "And if by some mischance he does, we will throw him back into the sea. Once you choose a new Warden of the Eastā"
The king groaned. "For the last time, I will not name the Arryn boy Warden. I know the boy is your nephew, but withĀ TargaryensĀ climbing in bed with Dothraki, I would be mad to rest one quarter of the realm on the shoulders of a sickly child."
Ned was ready for that. "Yet we still must have a Warden of the East. If Robert Arryn will not do, name one of your brothers. Stannis proved himself at the siege of Storm's End, surely."
ned's first reaction to robert bringing up the potential threat of viserys/daenerys is complete dismissal and a sinking feeling that robert has lived in the past so long that it's now the only language he speaks. this whole conversation (which i've only excerpted) has ned continuously brushing off robert's blustering in favor of addressing a more pressing issue: the wardenship of the east, and the lannister influence over robert's court. ned's dogged practicality clashes with robert's quickness to rage
the divide there is obvious. robert is in many ways still fighting the rebellion. ned has put down his weapons and catalogued the scars. it irks him that the lannisters benefitted from treachery & dishonor, and when ned sees gregor clegane (who raped elia and killed baby aegon) in king's landing he watches the man with "disquiet," against his own explicit policy of not listening to nor judging men based on rumor (speaking of! daenerys' dragons are, of course, little more than rumor in westeros)
"Robert, I ask you, what did we rise against Aerys Targaryen for, if not to put an end to the murder of children?"
"To put an end toĀ Targaryens!" the king growled.
"Your Grace, I never knew you to fear Rhaegar." Ned fought to keep the scorn out of his voice, and failed. "Have the years so unmanned you that you tremble at the shadow of an unborn child?"
i think it's clear enough by now. ned does not share robert's deep hatred of all things targaryen. he rose in rebellion because he was pushed to the brink, the murder of his father & brother among other northern noblemen by aerys, lyanna missing, the call for his and robert's head by aerys, injustice after injustice and even then, ned was fighting aerys specificallyāyou can listen to grrm's thoughts on the matter here if you'd like. he cites the fact that ned was "radicalized" by a "personal grievance," i.e. reluctant to conflict until the situation became personally unbearable, despite the immorality of aerys' actions pre-dating rickard/brandon's executions. ned's clashing with the lannisters is not dissimilar in that, despite his distaste for them being 14 years old, he's only moved to act when his loved ones (jon arryn/robert/bran/sansa and arya) are affected.
AGOT Bran I also comes to mind, where we get a crash course in ned's ideas of justice, ranging from theon's hostage/ward presence, to swinging the sword himself, to the conversation he has with bran about bravery and duty.
to answer your question on whether ned would change his mind about assassinating daenerys should news of dragons hatching come to him, let me bring into context ned's three dealings with potential threats he takes seriously:
first, AGOT Catelyn I, where they speak of mance rayder king beyond the wall as well as the supernatural Others, who ned immediately dismisses as a fairytale (another clue on how seriously he'd take rumors of dragons hatching):
["]The day may come when I will have no choice but to call the banners and ride north to deal with this King-beyond-the-Wall for good and all."
"BeyondĀ theĀ Wall?" The thought made Catelyn shudder.
Ned saw the dread on her face. "Mance Rayder is nothing for us to fear."
"There are darker thingsĀ beyondĀ theĀ Wall." She glanced behind her at the heart tree, the pale bark and red eyes, watching, listening, thinking its long slow thoughts.
His smile was gentle. "You listen to too many of Old Nan's stories. The Others are as dead as the children of the forest, gone eight thousand years. Maester Luwin will tell you they never lived at all. No living man has ever seen one."
second, ned's growing belief that the lannisters are behind both jon arryn's death and bran's fall, and how robert would react to it:
This was the boy he had grown up with, he thought; this was the Robert Baratheon he'd known and loved. If he could prove that the Lannisters were behind the attack on Bran, prove that they had murdered Jon Arryn, this man would listen. Then Cersei would fall, and the Kingslayer with her, and if Lord Tywin dared to rouse the west, Robert wouldĀ smashĀ him as he hadĀ smashedĀ RhaegarĀ Targaryen on the Trident. He could see it all so clearly.
third, ned's plan to use theon as a means of getting balon greyjoy's fleet should there be war to come:
When the door had closed behind him, Ned turned back to his wife. "Once you are home, send word to Helman Tallhart and Galbart Glover under my seal. They are to raise a hundred bowmen each and fortify Moat Cailin. Two hundred determined archers can hold the Neck against an army. Instruct Lord Manderly that he is to strengthen and repair all his defenses at White Harbor, and see that they are well manned. And from this day on, I want a careful watch kept overĀ TheonĀ Greyjoy. If there is war, we shall have sore need of his father's fleet."
so basically: a heavy reluctance to conflict. a deeply-held confidence in the martial power of the north to preserve itself. a miscalculation of how the recent conflict in which balon greyjoy's sons were killed or taken hostage might have permanently soured any possibility of allyship between the north & the iron islands.
so do you see that i do not think word of queen daenerys nor rumors of her dragons would necessarily move ned to any sort of proactive violence? the concept of 'swinging the sword yourself' is also one that makes me strongly disagree. ned would never agree with the idea of assassinating daenerys targaryen, or anyone really. it's not his moral code nor is it really his game
[T]he man who passes the sentence should swing the sword. If you would take a man's life, you owe it to him to look into his eyes and hear his final words. And if you cannot bear to do that, then perhaps the man does not deserve to die.
"One day, Bran, you will be Robb's bannerman, holding a keep of your own for your brother and your king, andĀ justiceĀ will fall to you. When that day comes, you must take no pleasure in the task, but neither must you look away. A ruler who hides behind paid executioners soon forgets what death is."
That brought a bitter twist to Ned's mouth. "Brandon. Yes.Ā BrandonĀ would know what to do. He always did. It was all meant forĀ Brandon. You, Winterfell, everything. He was born to be a King's Hand and a father to queens. I never asked for this cup to pass to me."
It was all too much. For a moment Eddard Stark wanted nothing so much as to return to Winterfell, to theĀ cleanĀ simplicity of theĀ north, where the enemies were winter and the wildlings beyond the Wall.
i also would just pose the question of why ned would be disappointed in jon for bending the knee at a moment when the north is in dire straits, the lannisters hold power in king's landing, and winterfell is occupied by the boltons? how does this square?
daenerys coming north & displaying concern for the northern people in a direct parallel to alysanne whose visit remains fondly remembered would, i believe, be a metric ton of goodwill that jon would have to be much less adept than he is not to recognize. robb, ned's actual narrative successor, made the mistake of not allying himself with renly, remember? and keep in mind jon's relationship with northern xenophobia (against the wildlings), in the middle of descending winter/Others, during a war built on many a personal grievance of his own (deaths of ned and robb, his missing siblings, theon greyjoy's role in winterfell's usurpation) has him stuck between a rock and a hard place already.
oof this is a whole essay now, isn't it? i'll wrap it up but here's two last quotes regarding northern attitudes, to be put in context of daenerys' potential involvement there:
"Renly Baratheon is nothing to me, nor Stannis neither. Why should they rule over me and mine, from some flowery seat in Highgarden or Dorne? What do they know of the Wall or the wolfswood or the barrows of the First Men? Even their gods are wrong. The Others take the Lannisters too, I've had a bellyful of them." He reached back over his shoulder and drew his immense two-handed greatsword. "Why shouldn'tĀ weĀ rule ourselves again? It was theĀ dragonsĀ weĀ married, and theĀ dragonsĀ are all dead!"
"WolvesĀ andĀ womenĀ wed for life," Haggon often said. "You take one, that's a marriage. The wolf is part of you from that day on, and you're part of him. Both of you will change."