Were this 20 years ago, arguing such an authority's point might have been reasonable. However, common values have been questioned to such an extreme extent, admitting that you don't know what someone considers vile isn't entirely unreasonable. There are people nowadays who argue that killing an entire race would have been a great idea, and others who claim that any procreative sexual intercourse is rape, without exception. In the end, you're probably still right, but the past 10 to 15 years have been a bitch for common ground.