I don't think you need to bet the river, you have good show down value and I don't think any hand that beats you is folding. If the river is a diamond, then I'd be more likely to turn my hand into a bluff but generally I just don't think it's a good bluffing spot. How many aces have you got?

Preflop: Versus a nit in utg I like the flat unless there are mad 3bettors still to act behind or a looser busy fish with position on me with no fold button, then I am more inclined to 3bet and fold like a pussycat to a 4bet. I often flat this if there are fish in the blinds, I can use them postflop to get free cards sometimes or gain more information about villain's range.

Flop is fine for me and turn yes I'm concerned, however, we didn't 3bet so we are ahead of unpaired suited hands like 78/89/9T, 77/88/TT and more unlikely holdings like AJ/AQ/AK which are not going to (although it is possible of course) barrel the turn very often.

River: I think we can rule out the Ax stuff now so I can't see villain folding after previous actions, you said yourself the turn bet was a worry and from a tight guy the worry usually is justified.

I'd play postflop as you did but check behind river.