Angled

I was tricked by an OMC type last night and he possibly saved a couple hundred dollars.  On river of AQJx10, the grumpy old crab, out of position, faked a bet, then checked.  I held three jacks, and checked behind conservatively.

I knew he had a pair and a gutter the whole time, but did not know which one.  Turned out to be Q10.  The 10 makes him holding a ten less likely, and increases the number of kings available.  He never folds a king pre, limp calling all broadway hands.

What’s more likely, that he is angling for a showdown, or has binked the nuts at the end and checked?

Does a losing, passive coot always bet the straight because he knows I will check behind?

I’m beginning to think so and that I got this one very wrong.

(Note: if I had been in my rage of the night before, I’m 100% betting here on principle in order to have non straights in my range.  Aggravation apparently makes me a more balanced player.)