I say, look the guy up. You may call his bet a "value bet" but, realatively speaking, I don't see 1 pair winning many hands in LL Holdem. I agree that 99, TT, QQ, and KK will often call and you'll earn an extra bet. But typically, they won't raise with them. Checking this hand on the river avoids the delima he's faced with now. LL Holdem is about value betting but its also about protecting your stack.