That word is thrown around like crazy in the black community. It is used in songs and in everyday life. Once a white person says it though, all bets are off and they are a TERRIBLE person. The hypocrisy with that word is insane.
I don't think he should have said it but people blow things like that way out of proportion. Who cares if he doesn't want to have sex with black women? I'm going to go out and say that I find some black men attractive (just like I find SOME white men attractive) but I could never see myself with one sexually. That's just not who I am attracted to. I would never rule it out completely though. That does not make me a racist.
As far as talking about his sex life with women he's dated, he should learn that less is more. I think he was wrong to specifically name Jessica Simpson. I don't really have room to criticize though because I'm pretty open with people about my sex life, not that there is much to tell. However, I'm not in the public eye. I would never talk about it to a national magazine though and name names (no matter what the demographic of that magazine is)!