Ok, It's really cool to look your inputs into that hand.. especially when i'm the only one who knows the outcome of the hand lol
It is cool to consider ranges and stuff (personally i believe that this is a bit of overthinking.. but anyway it is good for the learning process). Even from that it looks illogical to me that villain would make this play with a naked nut flush draw, my hand and the board blocks every suited ace that could hit a pair here (8s, 7s and 5s are out there, if he has a FD, it is a naked one). There are way other profitable (and less risky) ways of playing the nut FD here, I would never ever take this line, as he would probably be behind anything that calls him.
Considering equity:
Equity Win Draw
UTG 42.36% 41.98% 0.38% AsKs, AsQs, AsJs, AsTs, As9s, As8s, As6s, As4s
MP1 57.64% 57.26% 0.38% 9s8s
The naked nut flush draw here would have only 42% equity against my hand and would probably be flipping against any hand that hit a pair on the board.
I have over 3k hands on villain, I know he's a OK opponent, and I'd never expect him to make this play, as it looks pretty -ev to me.
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Now, when we think about the value hands he could be jamming for protection against the draws here, that would be mostly overpairs, sets, and two pairs. Here are the equities considering, again, all the blockers.
Equity Win Draw
UTG 46.93% 46.18% 0.75% 77+, 55, 87s, 75s
MP1 53.07% 52.32% 0.75% 9s8s
(Equities calculated with Equilab)
Again, on this board, my hand turns out to be the slight favorite against those ranges. I don't know if I'm missing something here, but it turns out I believe this was a profitable call. As i said, too many cards could improve us to a nutty hand, and if the villain has a drawing hand, we already have showdown value.