"Isolationist" is not the right word to describe Ron Paul's foreign policy. Paul wants to advance free trade, diplomatic talks and so forth but he just doesn't want to interfere with government's internal affairs (i.e. have the CIA do something sketchy if there's a potential anti-US govt emerging), give out aid for the purposes of buying American weapons (e.g. Israel and Egypt) take sides during wars or start unnecessary wars. I agree with this policy. He fears the industrial-military complex which is a corrupt group in the US imo (i.e. blow up a bridge in Iraq and then have a defense contractor rebuild that bridge = transfer of wealth from taxpayer to industrial-military complex).
So your saying he's policy is to abandon any responsibility that America may have historically (Israel, Iraq, Afghanistan). Yet he isn't an isolationist.