Great question. Even thought my response comes 4 years later. I'm not sure either, but he was referred to many times during season 2, so5b4 they must have known they'd bring him back. He did do 10 episodes of The District from 2000-2001. Maybe that contract and/or schedule conflicted with season 2.

Well, I don't know if it was in season two or not, but I think (and please correct me if I'm wrong, but I recently saw the episode, I just don't know what season it was)that his character was killed off.