On the river we need to defend 62% of our range to prevent being exploited, which isn't difficult to achieve if we don't have a raising range on flop or (maybe) turn.
Working backwards, villain's bet sizing on the flop gives our range a big problem if we assume we 3bet something like 8% and call somewhere between 60%-70% pre-flop.
On the turn, we can again check/call comfortably and this time without as wide of a range due to our range that called the flop. Trips, KK, and TT-QQ w/ a FD will suffice.
By the river, our range is:
30% FH
35% bluff catchers (flushes, trips with Kd/Qd)
39% A w/o a flush/Kd/Qd
The FH and bluff catcher part of our range is more than enough to defend here, and since you'll raise A9 you can even raise some hands like the one you have if u want to for balance and/or you think he's getting a little out of line. But folding the river is fine also. WP.