Don't even see the problem. Sure, it wasn't the most appropriate thing for her to say, but I'm not gonna jump up and call her a 'racist.' It's easy to spout off the wrong thing in the heat of the moment when you're angry. I do find it hilarious that blacks can call white people all kinds of names and call each other 'Nopes' in front of us and whatnot, yet it's supposed to be the most criminal thing in the world when whitey (or anyone else) says it back to them. To me, it's all down to context. In the future, I have little doubt that this is exactly what will become of these oh-so-offensive racist terms... they'll lose much of their weight and impact and become basically like any other insult. Obviously, most would disagree and thus it wouldn't be wise to call people such today unless you want to be labeled something unpleasant, but morality evolves over time. And don't act like you've never said 'Nope' in private, even if it was just in the context of telling a racist joke. I can assure you that at least 95% of people have. People make too much out of mere words.
I also am humored by the fact that the guy wants to file charges. He should learn to accept that being offended is a part of life.