tldr: sometimes we lose here, but the price is right for a call; thanks for giving us a fun spot to think through!
As played, the river seems like a hard spot for villain to have smart bluffs. Your most natural flop semi-bluffs are AdXd and KdXd, and villain is donking into you after two great range cards for hero on the turn and river where those bluffs now have showdown value as high as AK. And, with a real hand, he's denying you the chance to continue selling your story with QdJd, QdTd, JdTd, etc., especially at ~60% pot. The river donk is also way too big to be a block bet, but I could easily see myself in real-time reading that as a sizing mistake rather than just a pure value bet. I'm curious if he's just targeting your top of range with his exact hand, trying to get it all in against 99, AA, or KK. You've obviously got at least 99 and AA through this line, and likely some KK, too.
It is nice that we don't have Ad. I'd imagine some portion of villain's range is AdXd that decided to play a check-call line, and I could see some villains trying to block bet an ace worried that you'll check back a rivered king, QQ, etc. The suited wheel aces up through Ad8d obviously unblock all your KdXd broadways that might shrug call a block bet, and maybe he's just trying to chopblock your AQ-AT. And it's legitimately valuable that we're beating other aces, and it's nice for villain here that if he as AX and you have AK, you really can't raise this sizing for value. But with a cutoff open and a button flat, a lot of those suited aces should be 3betting pre, right? Likely 3betting AQ-AT, and I'm sure finding SB 3bets with all suited aces at some frequency depending on player type.
I'm also sure there are a few combos that can be assigned if villain takes this line with 8x7x or busted diamonds, gets to the river, and thinks, "I guess I have to bluff now." Spaz bluffs definitely are a thing that happens.
I'm probably finding a call here in real time with no reads that villain is massively incapable of bluffing and with the fact that we're beating other aces trying to chopblock. He has one combo of 66, one combo of 99, 9s6s, and As6s. Maybe he plays Ks6s, maybe not. Even if you give him all loosey-goosey A6o and 96o, that's only eight more combos total. (Right? Bad at math, help). Max of 13 values combos?
Range-wise, I also don't know what better hands we're calling with here besides AK. Maybe we have enough AK for that to be our calling range alone, but we're likely river raising AA, KK, 99 and being shown the bad news. I think AK and A9 are calls, and then some of other aces might start falling off from there. I think A9 is an even better call than AK since they're functionally the same hand strength as played but A9 blocks 99 (if he's calling it pre rather than 3betting it) and 9c6c (if he's calling it pre rather than folding it).
After thinking through the spot, I think the main things that would make this a fist pump call would be that villain is very snug with 3bets pre from a normally very 3bet-happy spot (keeping all his AdXd in range) and that villain is thinking enough to chop block your aces that aren't AK or A9 and/or get thin against your KdXd or a frustrated and stubborn QQ.
Thanks for sharing!