Way too tight of a fold. Get it in here every single time.

I usually follow a simple rule: "don't fold sets".

The flop is good for BB's range, so you could be check-raising with a lot of hands. The turn brings in even more draws. He could easily have an overpair and be putting you on a draw. You only lose to TT, 88 and 77, and beat all overpairs and FD.

You say the raise could be a straight, but is he raising J9s pre from UTG+1? Seems somewhat loose. If he is, it's likely to be Jd9d or Js9s, because he would likely not call a flop check-raise with only a gutshot and no FD or BDFD.

So I would call.

I would call only, it is over 200bb deep and definitely underbluffed spot. Gi with bottom set maybe low EV/marginal compared to call.
River bluffcatch with top end of bluffcathers.