He either seems scared that you
have the straight or he's reeling you in to commit yourself. Pot is already ~$73, so you can't bet/fold this because of redraw odds
, as you already said.
I'm not going to comment on the flop raise because I don't think it's as terrible as some seem to think, but I'd take the fact he called the raise as pretty significant. Checking behind is probably what I would do. I'm not sure it's the best play with all the draws out there but because of pot size if he check/raises you're forced to go for stacks, and I don't think I want to do that.
If a blank hits the river and he still bets pot this is kind of messy, but it would look like a fold.