"If you are not black you don't get a say in the discussion" seems like a pretty fucked up viewpoint to me.
Personally I like what Drifting Spirit has said in this thread in response to the Asian person that said "nigga" to his black friends. If you aren't black, and if you say the n-word, you shouldn't automatically expect that your audience will accept it. If your group of black friends are okay with it, doesn't mean that every black person will be okay with it.
It's just a really simple way of acknowledging the people who have an actual vested interest in the matter.
You either choose to recognize this or fight for the right to say the word even if your input isn't wanted. It's not like anyone is asking for this to be enforced by law or anything. All that's being asked of people is some basic dignity and respect... which is apparently too much to ask for of people who claim to care.