Well, for one, holding a grudge against someone, especially as a server admin, is really immature, but, yes, what he did was wrong, but that doesn't mean we should deny him a chance to prove that he isn't the douchebag he is apparently perceived to be. Allowing your personal opinions and disagreements with a person to get in the way of being an Admin is wrong. I've said this before, and I'm going to repeat it now
Being an Admin is not a position of power, but rather a position of service to the community and server as a whole.
So, he can stay Ultra-Trusted for now, and when he feels like he has proven himself to the community and server, then he can apply to be a moderator. No one is perfect, and certainly mass -rep'ing someone is not a habit Admins should have. We can't have a community if we all hate each other.