That's exactly my point. Now that he has evidenced his mindset with the act - it's done, over - do we ignore it and say his racism is not a reason for concern? or do we continue to permit him to abuse the public trust because of his inability to comprehend a race-blind society? No, we toss him to the trash heap and tell him to settle out his racist tendencies with others in ways that won't any longer affect the public trust.
Do you think a judge that has the appalling lack of judgment such that he shows up at a costume party in blackface, with his wife as his arresting officer, has the capability of setting aside his biases when sitting in judgment of a black person? If you do, that's unreal. This guy didn't just wake up one morning and decide to be a racist - he is a racist likely from birth and as such should not be sitting on the bench.
All we know is that in this racially divided society of ours, he exercised exceptionally poor judgment by showing up in a costume that was guaranteed to piss people off. Why would he do such a thing? Hatred? No--I doubt it. If anything, he may be guilty of excessive racial naivete--precisely the opposite of the virulent racism you accuse him of.
As for his being able to set aside whatever biases he may have--I have no idea. There is a post earlier in the thread in which one of the judges said that an investigation of his case history showed no signs of bias.
Personally, I think that every human being on the planet has biases--tribalism and suspicion of people who are different from us are built into our DNA.