As much as I'd like to, when the ability for an admin to "ban" users from the lists was discussed, it was met by a large majority who didnt like an admin to have that much "power"

It was due to this, that the only banning feature in the list servers was the ability to ban someone from hosting.

I could maybe place the IP in the "Global Digiex Blacklist" which would block there IP from accessing any resource at Digiex (which includes my list). That wouldn't ban them from using any other list that actively mirrors mine (Contrabandent, Madskills etc). It would be a big effort for every list server admin to find a way to filter IP's and ban them.

Although that may not even be enough, they could just use proxies. change there IP, or use GIP Scripts to get past the ban. The best method is if people actually hosting games banned trouble makers. I've banned this guy from my games.