Why do people dissapprove of people who dissapprove of interracial couples.?

Why is it that objection to mixed race couples on ethical grounds ellicits the utmost hatred and scorn from the mes indoctrinated in political correctness, even as those same supposedly "tolerant" people curse, spit and hurl invictives to the effect that the offending individual is a "hater", "bigot" and all around dispicable person?