Discrimination based on race, positive or negative, is racism. If a black person is 'allowed' to use the word but a white person isn't, it's racism. Bit ironic since it's a racial slur, but hey. I'm aware 'white people' have a bad history with enslaving black people, but that does not really apply to all white people. Or even most of them. I'm white, but none of my ancestors had slaves. My ancestors lived in extreme poverty in a place so inhospitable that it was rare that people lived past 40 due to hunger, extreme cold, disease, and Denmark. So why am I stuck with a social stigma neither I nor my ancestors had anything to do with?
Either all people are allowed to say '******', or no one is. Otherwise, we're accepting racism as a social norm.