UTG PFR stats are 6%. That almost certainly includes AA, KK, QQ, AK and AQ a vast majority of the time.
I think we can discount these holdings a fair amount.
Leaving A9, KQ, JT. I don't think he bets the flop with K9, Q9.

Considering the worst possible scenario is he holds JT. We still have 20% equity.
With the overlay from the other villian I think the raise is fine.
If this fish 3bets, if you thought he was ahead before - you can be sure now, and can fold the river UI. If he 3bets, he's betting the river aswell and you have same/higher implied odds for the flush outs.

If he calls your turn raise and checks to you on the river, you earn the same from your flush anyway.

It also allows you to take a free showdown a nonzero amount of time when we don't improve on the river.

I'll conceed it may not be standard or possibly not the best play, but this can never be as bad as you're making it out.
I think it comes down to how certain you are that UTG the fish has you 'crushed'.