Substitute the word "cowardice" for "isolationist" and you get the proper interpretation.
Nothing conservative about cowardice.
I don’t see anything conservative about subsidizing European socialism by paying for their defense as were are doing with NATO, especially now when those countries are busy importing millions of people who want to destroy them. I also think there is nothing conservative about starting unending which wars we don’t try to win. I do not know what the correct balance of engagement is but I think if we had minded our own business and not engaged in Iraq, Lybia and Syria the world would probably be a more stable place. I think we should either try to win in Afghanistan or get out. We have spent a lot in terms of blood and treasure there in the last 5 years or so while doing not much of anything besides maintaining a presence.
Going into a foreign war with no particular American interests at stake is not 'heroic', but far too frequent. The yellow press has been fomenting various wars since the Maine blew up.
Read Smedley Butler's short book: War is a Racket.