What, for letting a gang of morons run his campaign? He knew what he was getting into. He knows there's a huge festering pool of racism in the USA pumped full of anecdotal "proofs" that black people get put ahead of white people for jobs when the cultural mythos is that "every man is exactly equal", and pumped full of "proofs" that every black man is a criminal because that's what they see on TV.
He also knows that the American population has been uniquely schooled into this level of ignorance because of policies he helped support, giving tax money away to rich people while starving the public education system, which would have promoted the critical thinking skills needed for people to walk away from coded approval of racist commentary.