Defamation sort of implies that there were lies told about Thaily. Without seeing the post, we can't know if there were. Saying "this person refused to accept my commission because I forgot about another one I'd tried to have them do" is not defamation (not saying that's what was said, just that it could have been something that simple--we have no way of knowing). Granted, the new edit shows that they were not supposed to publicly call people out like that, and were subsequently banned, but from what I can see the issue worked itself out, and the beware probably wasn't necessary. I still think it was done to 'get back' at this person.