Did you see Eminem on 60 Minutes last night? In the interview, Anderson Cooper asked Eminem about people calling Eminem a misogynist and a homophobe.
Instead of admitting he probably is, Eminem said, "I felt like I was being attacked," he replied. "I was being singled out. I felt like, 'Is it because of the color of my skin? Is it because of that that you're paying more attention?' There are certain rappers that do and say the same things that I'm saying and I don't hear no one say anything about that."
Now this interview was presumably taped prior to the whole 50 Cent thing last week, so perhaps he would not have said the same thing given the chance now, but I do think people are called out for being homophobes regardless of the color of their skin.
Race has nothing to do with it. I think it is probably more likely that no one hears the rapper saying it or it does not get out to the world. If it did get out to the world, and if people actually cared about the person saying it, I don't think race would play any part.