It's allowed for topic-starters to delete all replies to their self-mod topics. Restoring the posts would only be considered in special cases such as if their account had been hacked.
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 ?
I dont know if the behavior and posting manner has changed the last weeks of him or not , as i not watched him much.
Hopefully he can clear things with an statement soon.
Although I suppose if he hasn't received a warning, your post, which he is sure to read, serves as a warning itself.
I guess it can be seen as a warning or an note for future actions.