With no reads it would be hard to judge this river, but I would probably do exactly the same thing you did. No reason to stop on the river. If it's a scare card for you, it could be a scare card for him. Alot of players play A-crap and so it's an unfortunate River, but you just have to give it up.

I would say he had A3, A4, or A7 giving two pair the way he just called down. But I wouldn't say he didn't have A-low.