This user was actively conducting bot farming activities, we provided proves on that thread, furthermore he never came back
That happened a long time ago, and I don't really remember the specifics right now. But if I am not wrong, there is no mention of "bot farming activities", what they are, and why they are illegal in your TOS. You did say the player was part of a bot farm, but posted no proof of it.
If you don't mind, can you explain how bot farming activities look like?
even his Bitcointalk username was temporary
There is no such thing as temporary usernames on Bitcointalk. Newbies often create accounts, ask questions, get the answers they wanted, and disappear never to return again. It's the same thing for scam-related accusations.