Our line is fine, although a case can be made for making a thinnish valuebet on the turn. The main argument for checking turn is to induce bluffs from floats/air, but in this spot I'd tend to not put him on a ton of pure floats on an Axxr (a hand like QJ has terrible equity vs. your c-betting range).
River: I disagree a little with the idea that he can be value-betting worse on the river. His river sizing is very polarizing, and unless he's playing some sort of leveling game with you, it's extremely unlikely a reg will show up here with an A9/A8/A6 type hand. Generally AQ will be about the bottom of his value range on the river given his sizing, and even that I'd expect him to choose more of a standard river size.
He's taken a relatively passive line to this point (float flop, 1/2 pot turn), which is NOT indicative of a two pair type hand. I'd severely discount most combos of two pairs from his range, and sets as well. Plus our A blocks so many of his potential value combos. 65s for a turned straight is really the only value hand that makes a ton of sense.
On the other hand though, I don't see a lot of air in his range. Most of his pure floats would be hands like KJ/KT, which he's very likely to checkback on the river and very unlikely to turn into a bluff. The only bluffs I can see that make a lot of sense for him to get here like this are 86s, and 85s if he calls pre. If you have any sort of a read that he's capable of turning a 7x or 4x into a bluff, then we have a call. Again, I doubt he's floating the flop with hands like QJ/QT/JT because they have almost no equity on this board, but it's possible he shows up with them once in awhile.
Our perceived range here looks pretty marginal. When we just c/c his small turn bet, now he KNOWS we absolutely cannot have a big two pair or set. Our range looks like a medium-to-weak Ax, or a 76s pair + gutter type hand. Given that range, he has license to bomb the river, especially on a K river. So even though his potential bluff range is very narrow, I think he will pull the trigger on the river with that range a relatively large % of the time, given how we've played our hand thus far.
All in all, we're probably good on the river often enough to profitably call. Both his value range and his bluffing range are extremely narrow, but there's a ratio of value bets to bluffs probably can't be higher than 2:1, so we have a profitable call.
