Well I've been an online gamer for over 15 years now, I think...has the internet been around that long? hmm...well anyways let's say 12 years. I've played many many games, mostly shooters, hehe I guess this is kinda a "shooter" too! Many years on Diablo 2 (if you ever played D2 you know how many hacks/cheats/mods there were.) Ahem..now then...lost my thought, wait wait, oh yeah, ok...I was gonna say, and am still going to...right about, now. Uh, I never played and online game without "cheaters" hate that word...cheaters, maybe I just hate what it stands for. Ok so ... to the point now. Seriously.
Every game I've played online has it's poo butts, and every game sponsor/hoster (WGT/Blizzard/MSNGamingZone etc.etc.) swears they are secure, confronting and taking care of the problem. Only thing is, once it happens...it's over for us legitimate players. It spreads like a virus, infects the majority, and new strains keep evolving to get around the vaccines. As I witnessed first hand in a game I used to play, even my best friends who swore against the hack and cheats eventually gave into temptation for the sake of competing. Maybe this game is formatted and run in such a way that this will never come to pass? I think this is highly unlikely, and very unfortunate.
To answer the question...with good evidence, I would ban his ass and never look back. Cya buddy. That $#!+ can't be tolerated, not even a little bit.
Good luck WGT. More power to ya.