split pot on river, opponent flashes cards then mucks

[ericicecream]

Shorthanded limit game at a casino, no chopping and you are in a blind-blind battle against a guy who likes to play every hand and is running well, but obviously doesn't understand the game very well.

You have A6 and bet the AJ9K8 river, fully expecting that this guy will pay off with any king or jack (he called your c/r flop and turn bet) and hoping he didn't make 2 pair. He mumbles something that sounded like "kicker" and reluctantly calls. You table the A6 and he shakes his head and flashes A2 to you only and then mucks.

Do you just scoop in the pot or do you offer to split?