Ron Paul is now guilty by association with dead people:

[Paul and his supporters] have to take their lumps as well for echoing shameful voices of the past. The history of right-wing isolationism is that it has been a hotbed of classic and unambiguous anti-Semitism throughout the 20th century, as represented by leading-edge spokesmen from Henry Ford to Father Coughlin to Gerald K. Smith to the America First Committee.

Non-interventionism was the term they preferred, and the fact that Paul echoes them is understandably unsettling to a lot of people.