I think Vince is just a bit of a sulky kid underneath it all, not that thats a bad thing. he's brill and all but hes not really able to deal with his mega issues, which makes him endearing.
Its sad that he blames himself when its no-ones fault but Lucrecia's and Hojo's. I think that its his way of feeling conected to her, by blaming himself, by kidding himself that he could have stopped her.