A lot of those folks simply haven't thought through their stances on foreign issues to the same extent they've thought through their stances on domestic issues. They aren't intentional social imperialists; they just pay less attention the further away an issue gets, which means they fall back on the Democratic Party line or at best "this country is bad but we shouldn't get involved."

In short, they're reachable. If we can't move those people in the right direction, how are we going to build a mass movement?