KQ is quite a bit more likely for him to be holding than smaller set (16:6).

However, you've got outs for the boat, a small chance that he's loose enough to be in there with AJ for top two, a small chance that he's overplaying AK here, and a small chance that he's flat out bluffing (but this is unlikely...look at that board, and there's 3 people behind him yet to act if I understand correctly).

If there's any chance in my mind that he'd play AK/AJ in a manner consistant with the action up to this point I have to make a call here. Only against somebody super tight and conservative can I tell myself that KQ is likely enough for a fold to be right. Heck, even then you may still have pot odds to call as long as a smaller set is still a possible holding for him (then the combined chance of either already being ahead OR catching a boat might make the call +EV even though he most likely has KQ)

In other words, I'd have called too. Tough break