I would bet turn for value he has more combos of weaker flushes and maybe Kx and Q9 calls u, river I don't think u can get value from 2 streets so my plan would be to check back river.
Think of it this way: the chance of him having As is close to none cause he didn't 3bet pre nor did he gii otf. Since QsX combos are such a small amount you need him to do this with very few other stuff, snap call.