Might the author be overreacting a bit to this new law? As I understand it, it doesn't put that much of an onerous demand on forum operators.
Then again, maybe he's just burnt out from running these sites and this was the final straw. I can understand if he wants to pack it in after so long, and this is as good reason as any to call it a day.
Though, has no-one in that community offered to take over? Forums do change hands now and then.