Could you imagine a white comedian saying the opposite?
I loathe the very existence of political correctness.
Chris Rock had the exact same joke years ago about white people voting for Jesse Jackson and waking up the next morning to find out that he won.
The link you posted doesn't even show him saying not to vote for her but even if he did it's not a big deal, it was obviously said tongue in cheek.
In any event I understand the sentiment. It has nothing to do with political correctness. Obama is an articulate black man who has come closer than any other black man to attaining the highest public office. He is on a very short list of black role models that are not athletes or entertainers.