The centrists are afraid to censor communist speech because the masses would object. And they are afraid to let white supremacy and Holocaust denial be defeated on their own in the marketplace of ideas because the affinity of their own beliefs with those ignominious ones would become too apparent. So they take the cowardly course that by establishing them as arbiters over what speech is acceptable (using the most odious views to create a precedent) sets the stage for future attacks on communist and other dissident speech, while preserving a cartoonish view of rightism as the inexplicable quirk of a few extremists having nothing to do with mainstream capitalist politics.