> I just don't believe it's accurate.
I have no idea why would you accuse GP of lying. You don't know him. Do you routinely judge if a person tells the truth based on some words he used?
Also, you confuse the GP's feelings about the situation right now with his attitude back then. Back when it happened, he didn't know of a 3 months long plot against him. Now he does know. He was shown the (obscenity censored because it would apparently alter the meaning of my post) documents, he read it black on white. Just before getting fired, too. It's nothing strange that his wording now is emotional and blunt, it says nothing about how he was back then.
Lastly, of course, there are polite ways of telling people to censored, you know why off politely. It's what assertiveness is all about. There are people, however, who don't really care about the form: they just can't stand others disagreeing with them. I don't think it's that rare a trait. How about that line of thinking:
"He's too polite, he's trying to hide something. And he dared to disagree with me, his superior. More than once! I don't have the time to deal with a time-bomb like him, which can blow up behind my back at any time. I need an army of easily controlled people to help me further my career. Yeah, it would be safer to spend a few minutes more and slip a couple of lies when working on his evaluations."
Preparing reports which are not true, yet are not outright lies, and which make some person look really bad doesn't really take much time. Especially if one does it for a living.