Just to add a little to the discussion, I suspect that the "not like us" messaging is mostly a right-wing thing, while there's more of a "don't contaminate my fluids" argument from the far-left.
Neither is a rational argument, and still trigger the same disgust and fear, but tend to have different implications for outgroups.
Neither is a rational argument, and still trigger the same disgust and fear, but tend to have different implications for outgroups.