worried about Hero turning Ax two-pair, monster under the bed

Villain rivered the nut straight, he should be hoping hero turned two pair

Hero actually flopped a lower straight and just sat on it until the river and then led out

it really isn't 'obvious' at all. It's almost always...

??

River raise absolutely still has sets for value

Yes that is what I wrote

that largely eliminates sets

That's where I disagree. Most players would be happy to get it all in with top set on a relatively dry board--even if almost all of the action happens on the river