Because he's been arrested several times. He has to be unusually stupid or plain incorrigible to see that he has a future in football, a free ride at school, a possible NFL career, and yet still be dumb enough to burgle a frat house. This is not the kind of kid who's just looking for another chance, this is a guy who's had chance after chance after chance after chance, and he's screwed them up every time. It's hard not to label a guy like that.
He's had many other run-ins with the coaches at Oregon than just some arrests. He really, really burned his bridges there.