In this case I think the user has deleted a lots of posts either it might be for changing hands or something else.
You might be right about the reason, he deleted his post which made his rank drop to Jr member because his activity points loss. After all, deleting a post is not a reason to suspect a user has changed hands, I think this kind of thing can still be done by every user in this forum as long as they think the post is not important.
Also I don't see bpip noting this account changed its email and password recently so any suspicion of the account changing hands at this point is very unlikely. About account above, I think he's still the same user without too much suspicion about it on my part. But if he cheats on you, then he should face the consequences.