and going one further.
what could he have? 5x seems unlikely since you think he is solid and would have folded pre.
JJ? unlikely, u block an out.
KK? would have 3bet pre.
55? hard to flop quads.
check behind with a 5 on the turn? why, he wants to play for stacks?
check behind with KJ? why would he do that if he decided to shove the river?
hehe just fooling around, i stick to my story, we should fold, just wanted to show that we can always find a reason to call if we want to