If a black "comedian" is as unfunny as the type of person who bitches about how white people can't tell racial jokes, they wouldn't be able to make white jokes because they wouldn't be a comedian anymore.
It's not about how far they push it, because it's pretty damned hard to push farther than Daniel Tosh. He just does it in a funny way and thus gets away with it.
The key to remember is that the white people who bitch about not being able to tell racial jokes just aren't really funny. When you aren't funny, the joke just sounds like some racist ****. They aren't victims, they are just incompetent. Trust me, I'm white and I tell racial jokes all the time. I've never been arrested for it. Nobody has ever shot me for them. I have been called a racist by some who consider any racial humor to be racism, but the people who have called me that have also been the ones who get really offended over piddling **** anyway. Why would I let them dictate what I can or cannot say?