Refusing to say anything positive about a civil-rights legend – because he didn’t like him.
It’s more than that. He has to signal to his base that civil-rights are a bad thing, and white supremacy is justified. See also…
…it’s all about reframing things as “giving them a chance to work”, rather than, “allowing them equal status and rights”… and that version of “doing more for the Black community” goes down well both with his white supremacist supporters (getting Black people working hard, they can get behind that) and others who support him and view everything in terms of earning money, and nothing else, including his small but electorally vital base of ecomonically right wing black and hispanic supporters.