So its possible if he keeps deleting or editing his old topics without writing something in here , that the Account maybe got hacked or sold ?
Unlikely.
He's still posting, and he still has the same signature. My guess: he's laying low because at this point the amount of drama he caused is only making things worse for himself.
Perhaps there should be a time limit on self mod. I can't think of a good reason to delete posts months later.
I can think of a reason:
It's self-moderated to keep the topic as compact as possible (for more efficient scraping).
I don't often delete posts to keep some Q&A, but once there's enough to delete to make the topic a page shorter I do it.