I think it's a bit unfair to say that Green Pippins doesn't see Tenna's complexities and only sees him as a spoiled manchild and horrible boss because... that's the facet Tenna shows to him and all his employees.
This is the sprite Tenna makes when he's threatening or extremely upset. The music stopped when he made this sprite, and then sped up; this happens during tense moments. The whole scene is tense. Abuse isn't just about physical violence. This is workplace abuse.
And the manchild thing, we also have this dialogue later. I'm not going to criticize Tenna wanting an antenna massage because I assume the real Mike did it without being forced by the contract so that's okay, but Tenna specifically wanting one of the Mikes for a massage and being disappointed that it's not the specific Mike he wanted (come on, he clearly knows it's not the real Mike, the "Now bring him ou or I'm tightening your contract" as if Green Pippins had any control over that... Tenna knows much more than people give him credit for, he knows it was Spamton and humiliates him, he knows it was Rouxls and talks about his ass and that he's stupid).
But then he asks him to climb him, instead of perhaps shrinking or sitting down to a safe height? That's very spoiled.
To portray Green Pippins as never caring about Tenna's feelings is dishonest, because we see his sprite showing concern for Tenna. Toby Fox chose to have him remove the head costume just so we could see his worried expression. This means something.
People vilify Green Pippins just because he's opposing Tenna and stated the obvious: that Tenna treats everyone who works with him like trash. We also have Cowboy Mike and Pluey enjoying being Mikes, and it's almost never mentioned how much they both also enjoy deceiving Tenna and "abusing their position of power". And so far, Green Pippins has only said that he wouldn't massage Tenna until he stopped treating everyone like trash, that's not what abuse of power really is.
Just as Tenna is complex, Green Pippins' situation is also complex. It was proven throughout ch3 and the dialogues of the fake Mikes in ch4 and ch5 that Tenna doesn't respect his employees, the only person he treats well is Mike. He wasn't going to listen to a "dice boy" (this was extremely classist and meant to belittle and humiliate, nobody should refer to their employees that way). Green Pippins also didn't want to pretend to be Mike for the lolz, he started pretending to be Mike because he was tired of Tenna taking out his personal problems on his employees (workplace abuse).
But it's quite interesting to reflect on the fact that the only one who stands up to an abusive boss is the one who receives the most backlash and is vilified, while we have two other characters doing the same thing and openly enjoying it more than him.
Green Pippins spends far more time insulting Cowboy Mike than anything else. And Green Pippins mistreating other characters doesn't negate the fact that Tenna mistreats them too. Two people can be wrong at the same time.
I even saw people saying things like "oh but Green Pippins can just leave!", besides being extremely victim blaming, that wouldn't change anything for Tenna because he would still be an abusive boss who wouldn't reflect on his actions. Green Pippins isn't lying when he says Tenna treats all his employees like trash.
We can like characters and acknowledge that they did wrong things and were abusive, and believe they deserve healing and grow as a person without looking for excuses or justifications for their wrong actions. One of the protagonists is Susie, who threatened to kill and rip Kris's face off. She has a bad and difficult life, and none of that excuses the way she treated Kris, but we all still love her and appreciate that she's being better and acknowledging what she did wrong in the past.