They would be pretty shocked!
They’ve both been father figures for Sam in a life where he can’t predict where he’ll end up next, and he’s grateful to both of them. If he could bring Walt somewhere safer, he’d love for them to meet. He knows how Walt feels about hunters, which is the only reason he hasn’t brought this idea up.
However, Walt and the rest of the family are warming up to Dean, so who knows what the future holds…
Brothers Apart 