I don't think Kav was wrong, I don't think Keith has shown his true self at all, he's legged it from any confrontation in the past and he's done his best to keep a smile on his face, it slipped when the issue with Perez and Alexander flared up.
We knew this was Kav, we saw it on the Big Reunion, it's not so much that he's bitter at people I think he's bitter at himself and paranoid that people are against him, even if they ain't.