I don't know what wars he would have been for or against.
But that is why Congress is suppose to declare war, to go on record of its commitment to it.
As for a 'self-centered' policy, all nations policies are suppose to be 'self-centered' and that was exactly what Washington warned us about when he told us about 'entangling alliances'.
The American Gov't has a responsiblity to the American people and no others.
Our power is not unlimited and we had better recognize that before we go the way of Persia, Greece, Rome, Spain, and Britain.
Our greatest asset to the world is our very existance as the freest nation on earth and that is what will need to export to the world, the American ideal of freedom.
We cannot force it on the world.
No we should just stand by and watch nation after nation fall into darkness.