The problem is not so much that kent was manipulative. It is that he is currently manipulative. And like I'm sure he didn't just turn into a manipulative ass after the draft, in fact it's pretty clear he was that before the draft but it's literally on the page in the present.
Like parse II when Shitty is talking to Bitty. Even if we pretend we don't know shitty is a little unreliable. What do we know? Kent brought the Stanley Cup to a kegster. Like what reason could he possibly have to bring the Stanley cup to a college party if not to show Jack what he's "missing out" on? If not to make Jack feel bad?
Parse iii it's beyond obvious "it's people like me who care." But we also see him openly shit on the progress Jack has made, mocking his every choice, putting down this family Jack has made. Throwing Jack's dad in Jack's face. And it's clear this is not the first time they've had this conversation. Presumably they had it when Kent brought the cup.
If Jack really did treat kent like he treated bitty in year 1 then kent KNOWS Jack doesn't like this, doesn't want kent to do these things, and knows it makes Jack feel bad.
Yes teenage kent was probably manipulating teenage Jack. But the bigger issue is that adult Kent is still trying
