Unicorn was banned for a serious breach of the rules for which anyone would have been banned. We try to apply rules fairly and uniformly to all members of the forum. Any sigh must be directed at Unicorn's mis-behaviour.
Their account name (login) was never changed - only the display was changed. I didn't know it would revert on a ban being given, and am actually surprised that the software does that - I consider it a bug. I now know how to deal with it, though, and may change it back in a while. [later: done, I think]