Disagree. If I see Professor Gates in Harvard Square and if I start yelling, and carrying on, and shouting the n-word, you can bet I will be arrested for disorderly conduct (like he was) and in addition, I will be slapped with a Hate Speech charge.
Racist statements ARE illegal -- if made by a white.
I have seen klan rallies, and that word gets tossed around plenty. I've been called cracker and no one went to jail for it.