I have no clue either, but I've learned that people will do very strange things for their own internal reasons.  Think of Munchhausen's Syndrome, for example.

I don't know if this falls under the plagiarism rule or not, since what he stole wasn't the written word, which is what plagiarism is defined as (AFAIK).  It's certainly dishonest if true, and if he doesn't get banned for this (which he may very well not be), it surely would be grounds for some negative trust. 

Props to OP for sniffing this out and contacting the person who apparently created the drawing first.