"WRONG ANSWER"
TW: Yapfest, spoilers
I don't think there are/I didn't see enough people talking about this.
First, I want to address this theory (and therefore give credits to @thesillyphilly 'cause reading what he wrote plus the update (that particular panel) made my mind race all night about this). This because whatever meaning I scrutinized in the insomnia caused by all of that will be related to it.
In this vein, we have one single clear and fixed idea: Bendy is a sixth piece of the machine that is needed to turn it on, activate it, and thus give the sick toons a chance to live (including himself): being either the plushie that literally looks like him or the ink bottle (which kinda may have been foreshadowed in this panel).
Regardless of which one he is (or even if he's both and just embodying one of them will finish him off), this, in fact, may also be a good explanation for why Bendy is the only one who can see and read the map (which, if so, would seem to me to be one of the many, many smart decisions Nort and Fly made while writing this, because, if you remember, in Bl•gTh•Gr•atRo•ge's comic, Boris could also see the map).
According to that, we have two options, excluding in advance a zero option in wich Bendy, being one of the pieces, does not have to sacrifice himself for the machine to start working and can activate it without putting his integrity on the line.
So, first of all: we have the meaning of “WRONG ANSWER” as if they were telling Boris that he made a bad decision, that it is wrong because it will indeed be executed but will bring negative repercussions that he would not have wanted. There was no correct answer here, and Boris was responsible for what would be sacrificed: and he, despite everything and unconsciously, chose Bendy.
Here we could propose a scenario in which Bendy has to die in order to activate the machine and thus cure the Blot of the other toons; if he doesn't, the machine won't activate and he'll die from the disease anyway, so it wouldn't make much sense not to do so.
And, even though Bendy was going to die one way or another and it was almost fate or something like that, Boris was the one who insisted so much on following the map and on the general idea of finding the ink machine. One could very superficially attribute responsibility to him, right?
.... But what if they were given a choice at that moment?
And here comes the second meaning I could derive from “WRONG ANSWER,” which is as if they were telling Boris that his answer is wrong, not because it was something he really didn't want, but because tacitly it's not what's going to happen, as if they were breaking (even more, perhaps) the fourth wall. Here, in fact, there was a correct answer, and Boris (although he was still responsible for what he was going to sacrifice, which I'll explain in a moment) didn't determine anything with his answer. It's as if they were just giving him the opportunity to GET RIGHT what was actually the correct one.
If Bendy is the wrong answer and is not what Boris is going to sacrifice, what is the right answer?
The map is something they will need, in theory, throughout the entire quest; they cannot do without it because it is the only way to reach the macro goal. So, like Bendy, it could not be “sacrificed” until the end of the story (again, in theory, because we are making these assumptions based on the information we have so far), but, unlike Bendy, the map is also not one of the pieces of the machine and would not need to be destroyed to activate it. By the time they have to turn on the machine, they will no longer need it (they will already be there) and if it was needed for some reason to do it, it wouldn't be a sacrifice per se.
And, on the other hand, Boris has already made it clear that he's not going to sacrifice his morals for...
Oh.
But he already has.
Of the two times so far that Boris has refused to compromise his morals over the whole machine thing, he has already broken that “promise” once.
Yes, Cuphead's soul is safe (for now XD) and he will obviously return to the earthly plane somehow and be part of the quest as one of the protagonists, but, for Boris, he is dead, and he is dead by his hand.
He “killed” Cuphead because it was either his life or Bendy's.
He sacrificed his morals because it was either that or Bendy's life.
So what assures us that, under very similar circumstances, it wouldn't happen again?
Maybe this is a bit far-fetched, but imagine a scenario in which, yes, Bendy can sacrifice himself and save the rest of the toons who have the Blot, but he can also (due to mystical aspects of the script and his relationship with the machine as one of its parts, which I am unable to elaborate on because I have already burned all my remaining brain cells writing this) activate the machine without dying in the process, but healing only himself.
That has many, many gaps, I know, but just imagine it.
Imagine Boris with the final decision, deciding to heal Bendy at the expense of many other toons.
Because it would be their lives or Bendy's.
It would be his morals, not killing anyone (because that's what would be happening if they Blot keeps spreading) or Bendy's life.
And we already know which path Boris takes in the face of that dichotomy.
And maybe I'm exaggerating a little, maybe I'm doubting Boris' determination and values too much. Cuphead was just one person and he was attacking them; the rest of the toons are millions of innocent people who have done nothing to them and who, in fact, are in almost the same situation as Bendy.
But imagine finally reaching the machine, after so many obstacles, so much risk, so much effort, so much hope and despair of being able to arrive in time, so much evasion of what was a fatal destiny, so many sacrifices, only to be told that you have to let the person who drove all of that die for the sake of a bunch of strangers, and, above all, to be told that, in fact, you have the option NOT TO DO THAT: it's either kill your brother who has struggled to get there and let the other sick people, who may have already accepted death (just like Bendy before finding the map), live; or cure your brother who finally had hope to live and let the rest of the world follow its tragic course.
Besides, after all (in the case of the bbros), it all started to save Bendy, not to become heroes.
Anyway, lots of loose ideas, perhaps poorly defended and/or articulated, but I needed to ramble on about this.
