Wp imo.

How is this not a call? What else do you get to the river with that you are calling? Especially as their are several draws out none of which came in apart from 6,4.

What do we lose to and what do we beat? We lose to AA, KK, flopped sets, 53, and 64, AQ and KQ and maybe A3 of clubs exactly? We beat all flush draws (of which there's actually a lot, loads of AXcc and K high draws and plenty of other suited connectors) and 86 and 98.

I don't think we beat any value bets as I don't think he's gonna value bet Q8 or Q6 if he even has them. And he never bluffs with a better hand so we just do the math. I count 42 combos of hands he has for value and 26 for bluffs. So if these ranges are accurate then we're getting the right odds to call. We're getting 2.39:1 to call so we need about 30% equity and we have almost 39. This is also assuming that A) Our opponent is bluffing too much by using his nut flush draws when he doesn't need to, though this also takes A3cc out of his range (while I never put AKcc in his bluffing range at all) and B) Our opponent is also bluffing with all of his gutshots and is opening hands like 96s and T6s. Point B isn't much of a stretch because if we don't have a Q then we don't often really have much more than a gutshot here so he can bluff pretty profitably with those weaker hands, we more need to consider point A. That said, if we take all Axcc out of his betting range, we still have enough equity to call. It's much closer to break even but slightly winning. This bet size for him becomes correct when we take all out of his range while leaving his value betting range the same (which may actually be slightly too wide).

At the end here I think we need to decide which Qx to call and which to fold because our range is relatively small on the river here. If we just call 100% of our Qx we're calling too much and open ourselves to getting overbet and a lot of annoying stuff. Q9 isn't a great hand to call with, I'd rather call Q6 as we're blocking more value hands and not as many bluffs, whereas with Q9 we're only blocking bluffs. So do your analysis, follow what range you think your opponent has and consider their betsize. If you think they have too many bluffs in their range or not enough (like if they really like betting nut flush draws or really don't like better gutshots) and evaluate based on that. If he's betting nut draws here then we call for sure. If we think he's underbluffing then we can actually call with Q6 and fold Q9.
I tend to do bigger analyses but it helps me to write them too, I hope you find it even slightly helpful.

It's true that your hand is nothing else but a bluff catcher
So if you think villain is playing value-heavy, you can fold the hand.
However, If I were to be playing against you and I know you're folding Qx on this board run out, I'm triple barreling you every time as it's a super weak fold.

betsize is approximately 0.33, 0.66, 0.75 each street
You're under-defending your range if you're defending too much less than 0.750.60.57 = ~0.26(26%)

In terms of pure strength of your holding, the margin will be around weak 7 (76s, 74s), which means we are either calling/raising anything better than that. Where is Q9o? Q9o'd be around Top 12% of your range at river. So basically if you're calling every better hand than Q9, you're still defending "less than half" of what you're supposed to be defending. This opens a great opportunity for your opponent to bluff you out and this can be potentially very big leak if you're always playing your marginal hand like this blindly.

+)

Well we can consider some blocker effect additionally.

I believe it'd be good to choose blockers such as A5,K5s,A4s,A6s(+65s,54s) as good calling/raising candidates, (A is better blocker than 4 for both raising and calling because his value range is less about 64 and more about AA AQ)
and in that regard you can give up some bad 7's such as 78,79,7T,7J and FD blockers maybe

++)
Regarding that BU's opening size is pretty thoughtful, I don't think BU'd be the worst player in the room. And if BU is not the fit/fold type player, that kinda river is spot where aggressor tend to be overbluffing. Frontdoor FD,Backdoor FD,68s,89s,96s missed and only 64 completed its draw. You didn't raise the flop against relatively small cbet, and turn as well, so your opponent is less worried about you holding monster hand by river. Increasing betsize is pretty suspiscious as well for me. But since I wasn't playing the table myself, I wouldn't comment too much in exploitative persepective.