I don't agree that a solid thinking player capable of making some moves is jamming the turn with his AA/AK/2pr hands with as high a frequency as you suggest Stu. I think its entirely plausible that he decides to call/call. If he realises that combo-wise hero has far more draws that made hands (which he probably does) then call/call is obv the nut line for him
I don't think you can give him credit for being able to jam his missed draws on this river without giving some credence to the fact that he can realise that call/call is a great line here vs an aggro villain that will be capable of jamming missed draws himself.
The thing is Dan... this is actually wrong. And the reason it is wrong is to do with the SPR on the turn, combined with the extremely wet board texture.
If villain jams the turn, hero only needs ~27% equity to call... which means he is actually priced in with his strong combo draws (so villain can get the money in right now rather than hoping for him to bluff it off on the river, whilst simultaneously 'protecting his hand' - or, even better, villain gets hero to fold in a spot when he should call). And if hero has a bare flush draw or straight draw and has to fold then this is good for villain too.
Do some equity calculations (or a crEV/pokerazer sim) comparing the EV of forcing hero to fold a bare FD or SD to the EV of allowing hero to preserve his equity in the pot by letting him see the river. First, be generous to your viewpoint and assume that hero will bluff
every single time he misses and villain will
never ever call when hero hits his draw (even when it is the 'semi-disguised' straight draw) and you will see it is very close. Then change the assumptions a little and assume that hero will
sometimes choose
not to bluff the river when he misses, and might
sometimes get paid off when he hits... and you will see that jamming the turn becomes clearly the most +EV line for villain when he has a made hand which he intends to take to showdown.
Now obviously no-one does this sort of calculation at the table... but this is not the point. I am almost certain that IN GAME pretty much every competent player (and even most non-competent players) would still realise this intuitively/subconciously. They might phrase it in different terms - "The pot is really big now and there isn't much behind... he's probably not folding if I jam now so there's no need to continue to trap, plus it is time to protect my hand" or something like that. But this is actually just saying the same thing as the analysis in the paragraph above. And it is pretty clear and obvious too. The reason it would so obvious whilst actually at the table is mainly, as I said at the start,
due to the SPR on the turn combined with the board texture.
Try a little visualisation/empathy exercise... put yourself in villain's shoes and imagine yourself facing this turn bet, looking at the texture of the board, counting the effective stacks, and realising there is only another ~400 left to bet into what will be a ~740 pot after your call. If you still come back and tell me that you (or another competent player) would consider flatting with a set or AK then we will just have to agree to disagree - I think we've done this before in a thread

... But I think you'll see what I mean if you do this visualisation/empathy thing.
Btw, if the SPR was a bit bigger and/or the board texture was a little drier then you would of course have a point.
ADDITIONAL: I don't think I have explained the concept above very clearly. It is a really easy concept but actually surprisingly difficult to put into words. So I am going to give a really extreme example of the concept and hopefully it'll make sense and you'll see how it applies in a diluted form to the hand in this thread... Imagine it is PLO and on the turn the board is something like 67QJ with two flush draws. One player bets the pot, say £200 - and the other opponent JUST CALLS
leaving himself only another £100-£150 remaining in his stack. In this situation the opponent who just called can have a massive draw; he could have a 20 card wrap with two flush draws for example. But the one thing he CAN NEVER EVER HAVE is a decent made hand. In fact it is actually almost impossible for the caller to have
any showdown value whatsoever in this spot, even as little as say top pair no kicker. Because with
any sort of showdown value whatsoever to go with his draw he would simply push for his last few chips (for the times he is against a draw with no SD value). Does this make sense? And can you see how it transfers in a watered down sense to the NLHE hand in question?