"supporters of President Bush and other conservatives had stronger self-admitted and implicit biases against blacks than liberals did."
There's the key sentence. The data doesn't say that Republicans are racists, it says that they are more likely to be so than Democrats. All it takes is 11% of Republicans and 10% of Democrats being racist to make the above statement true. I suppose if you surveyed voting patterns of those who commit adultery you would probably find Democrats are more likely by adulterers. You could add murder, cheating, and stealing and I think the Dems would win on those also.
Actaully, what the survey says is that people an unscientific online survey found that people who said they were from places where Bush won were more likely to say that they they distrusted blacks than people who said they were from places where Kerry won. This whole study is worthless.