I used to run a forum and I sold everything including the database. A site has since popped up ran by our "technical administrator" from back in the day that is operating off an earlier copy of the database previous to it being sold. The database wasn't attained in a malicious fashion since they already had multiple copies of it. Any footing to for the original buyer to sue the technical administrator using the old database?
Of course there is cause if he bought the entire site with right to the content - he owns it and anyone else using a copy is infringing upon his intellectual property rights.