I was playing 1/2 nl live and was dealt AQ in the SB.

My stack was around $450, other two players in the pot on the turn were deeper.

The pot was straddled by the CO for $6. As I am not a fan of raising a straddle with the rest of the table to act, I just called, and so did 4 other people.

Six ways to a flop of K J 10.

I checked dark as I always do in the SB and a player in UTG+2 made it $20 to go. Three folds and the CO called.

I raised to $85 and they both called.

The turn was a 10. I bet $140 and they both called.

The river was a 6. I checked thinking I had to be beat with two callers on the turn. UTG+2 checked and the CO shoved his remaining stack of $400+. I folded thinking that K10 and J10 have to be in his range to call on the flop and turn like that.

Do you all fold here?

I talked to a couple of other players the night it happened and they were happy to just get stacked if one or both of the other players had boats.

First, the straddle is just an extra blind and dead money in the pot. AQ is a perfectly reasonable holding to raise. if you are only raising pocket pairs QQ+ in that spot you become very easy to play against.
Second, what is villains range/VPIP is this an active villain or is he captain nit. I think we can safely take quads, sets of jacks, and sets of Kings off the table as all these hands would be raising pre. This leaves only KT and JT as hands that beat us. I think that villain could also have flopped bottom end of the straight or realistically have a hand that had spades and a T in it 9T and think they were valuing the river with the shove. Bluffs would be missed spades and missed straights. When i beat most of their value range, all their bluffs, and only lose to a small percentage of their realistic made hands i call. Pot is 742 we only have 200 and change left at this point as well we are getting better than 4 to 1 to make the call. Which means we only have to be right once out of every 4 times we make a call in this spot.

"As I am not a fan of raising a straddle with the rest of the table to act"
Just to re-iterate Old English, - limping with AQ is a mistake. You have to get the pot heads up and give set miners poor odds. Of course this is high variance, but you do not want to call a raise with this hand, nor play a multi-way pot with it. So isolate.

I agree with both above. AQo is to strong of a hand not to raise pre-flop. When the straddle is on the CO your RFI/fold range is pretty much UTG+1 plus you are going to be OOP. Without raising you're letting a lot of weaker offsuit combos containing a 10 come along that hit that flop and can fill up OTT