Can black journalists be unbiased in reporting?

I listened to Juan Williams on NPR's Morning Addition last Thursday. It was an interesting piece that asked the question if a black journalist should be unbiased when reporting on the black community and it's leaders. The answer appears to be no and after listening to the piece again it seems to justify advocacy and omission as acceptable journalistic principles for "black" journalists. Looks like it's another step backward for truth and integrity in journalism.