You are right. Isolationist is a pejorative coming from the WW II era. It is applied erroneously to those who are non-interventionist (meaning don't fight other people's wars for them).
When one considers that the USA spent the first half of the last century fighting in Europe and the last half fighting in the Pacific. We start this century fighting in the Near East with low war beats about South American and African enemies. We have troops in God knows how many countries setting trip wires throughout the world. Neither the sun or the moon sets on the involvement of the USA. We are not isolationist. God help us.
Thank you. “Non interventionist” would be the best term.