It needs a very specific read to assume that a villain will bluffshove middle pairs here. It's a very scary spot to bluff at because your c-bet bluffing range just got there... obviously, and he would have to count on you to bet/fold JJ+ on the turn... so he needs to know that you're barrelling overpairs to the flop when an overcard hits. If you don't have that kind of history I think it's just way too much guesswork imo.
He probably slowplayed a set. it's a bad turn to raise, but then again he probably is bad.