Evoc, we understand the problem, but thing is, we couldn't give a fuck. I myself understand your situation, theres some pretty big assholes in Tremulous that would do every trick in the book, but thing is, the only good solution is to deal with it. Seeing how you show this player to be a threat to all idiot-kind, I suggest you stay away from any server hes on. If hes really that much of a jerk and an admin is around, he'll be kicked pretty quickly.
Right now, we only have your word on this. Maybe this topic is best under Server Admin Contacts, and notify the admins of the servers he has been abusing of his behavior. Provide evidence (Screenies) and maturely ignore him, I believe there is an ignore feature on some servers so use it wisely. You're a good player who does some mapping for Tremulous, so you shouldn't really waste your time on this guy because you should know what to expect from flaming turds.
Cheers, hopefully this can work out.