For the same reason that:
The NAACP is not racist, but a NAAWP would be.
The United Negro College Fund is not racist, but a he United Whitey College Fund would be.
It would be racist to give preference to white people when hiring, but not to give preference to black people through affirmative action.
The TV channel BET is not racist, but a channel called WET would be.
It’s racist to use the word “ni**er” if you’re white, but not if you’re black.
A black conservative is an Uncle Tom, but a white liberal is enlightened.
A white person that voted for McCain last year was racist, but a black person voting for Obama wasn’t.
Racism here, you make the call:
The Illinois senator won 43 percent of white voters, 4 percentage points below Carter’s performance in 1976 and equal to what Bill Clinton won in the three-man race of 1996. Republican John McCain won 55 percent of the white vote.
Fully 96 percent of black voters supported Obama and constituted 13 percent of the electorate, a 2-percentage-point rise in their national turnout. As in past years, black women turned out at a higher rate than black men.