AFAIK, isolationism means less government.
Until you get into the tricky part of telling me where to travel, and whom to do business with . . . .
Agreed, in fact, I'm not sure if "isolationism" would even be relevant to the discussion of big government/small government except in that less foreign intervention would mean less use of government resources.
Before Iraq, wars were things the Democrats always got into for the most part, Vietnam, Korea and so on. And Gulf War I conceivably was justified but I remember Conservatives who certainly didn't want to even go to that.