He had a loooong history of causing trouble. iirc, he started out with good contributions (he developed tremX) but he started causing all kinds of flame wars, spam, etc. I do not know what he did originally to warrant a permanent ban on his first account, but since than he has created and used somewhere near +-10 different accounts (all subsequent 9 being against forum rules).
And apparently Timbo got sick of banning his multiple accounts, and banned all of Turkey.
P.S. I'm not voicing any opinions here, I've talked to the person in question, and I don't find him to be bad in person, but I saw what he did on the forums, and I'm just trying to say what happened as I remember.