You can't just call down with A high here unless you know that villains range is extremely polarized. I would know because I've tried. Use PT or HEM to filter for your hero calls with high cards... turn it into a graph for the extra dosage of *puke*.
I agree that c/folding is probably better than donking the river as played, but I still think you're making your life very difficult by just calling the turn oop.

I don't quite understand why you put so much emphasis on THIS gutshot. I would c/r a gutshot with overcard.... But I would c-bet flop c/r turn loads vs a habitual floater.... a draw is obviously good because you don't need as much fold equity to make the c/r profitable. And I wouldn't get too hung up on the showdown value of A high here OOP and with another street of betting to come either.