Yikes--I'm pretty sure he'll be pretty upset about that if he isn't already. 

He'd been a member since before the merit system, so I don't think he started with zero merits.  Nevertheless, he was a pretty familiar face on the forum (at least to me), and it sucks that it turned out this way.  I don't know if more plagiarism was found or if the mods just didn't accept his reason, but we'll see if he appeals it.

My guess is that he forgot about it once the thread was locked or thought it wouldn't be necessary because it got locked.  And yes, that's exactly what he should have done once his mistake was realized--and here I'm giving him the benefit of the doubt in saying that it was a mistake.  I'm not a mind reader, so who knows.