It would not be immoral to suppress racist speech, but it might be imprudent.
Racist speech is immoral, just as murder is immoral. However, for prudential reasons, we tolerate this evil because we, as a society, judge the cost to society of supressing this evil to be greater than the evil itself.
One cost of this approach, however, is the promulgation of indifferentism throughout society regarding evil speech. "Hey, I can say whatever I want!"
We have a fundamental disagreement on this.
Cunnilingus:Where is the equal protection under the law?
Between man and woman is OK, but between woman and woman is Not OK.Fellatio:
Between man and woman is OK, but between man and man is Not OK.Anal Intercourse:
Between man and woman is OK, but between man and man is Not OK.
I predict that the Supreme Court will strike down this law.