I'm replying here with my information on this ban.
The grief trap named "NickHouse", which is located just outside the guest world's spawn city (by the massive pumpkin farm) had been griefed by a number of individuals. Those individuals did not receive any ban, nor did the grief trap repair itself. This led us (a group of mods and ops) to the belief that these players may have been using some hack or client to get around the grief trap. As part of a security measure, all those who griefed the structure without punishment, which included this player, were permanently banned until the situation was looked into. All in the investigation group were in agreement of this move. That said, not being the senior staff member present, I left the escalation of the issue to the op(s) that were present.
The ban was over a month ago, and I do recall taking screenshots. That said, I've had a hard drive crash since then and all my screenshots have been lost. For further information on this ban I suggest you discuss with AwesomeAlicia, as she (and a few others I can't now recall) were present to repair the damage to the grief trap. To jog her memory, I'll mention that we also (this day) repaired the all golden grief trap by the same spawn, due to an individual using powered pistons to grief it. This player, however, was not to our knowledge involved in THAT grief.
EDIT:
Now that I think about it, TheWholeLoaf might have been the one who actually found the grief. But I can't be sure. So much has happened since then.