Just to get people talking, I'll post my differing opinion.
I did not appreciate his method of disregarding political correctness, and I'm a serious anti-PC advocate. However, there's a difference between not censoring yourself to stick with PC and going out of your way to insult people just to prove you're anti-PC. I thought that Dr. Carson's message, whether it was what he intended or not, came across not as 'I'm gonna stick it to political correctness,' but as 'I don't care if I insult people because it's okay if you don't mean it.'
I don't think you can condone making jokes about minorities under the blanket of "no offense, but..." Ultimately, it does matter if you offend other people. You can't just say, "I don't want to be politically correct, so I'm going to go ahead and make insulting jokes."