SMA, just block him. We've all been down this road. He says something racist, flips out when it's called racist, then comes back and says something even more racist. He isn't from the US, yet feels he's the authority on what life is like for African Americans.
He's ignorant about his favorite topics, and just doubles down and gets more outraged.
Life is better when you cut those with no awareness of the limitations of their knowledge out of it. He won't learn, because he's convinced the world works for everyone as it does for him.