Dr. Barber appears to misunderstand his opposition.
Of course there were plenty of racist Trump supporters. There were also plenty of racist supporters of John McCain and of Mitt Romney, and they then had a black candidate to vote against. These people did not suddenly become racist because of Donald Trump, nor did they become racist because of Barack Obama.
Hillary Clinton lost against the second least popular presidential candidate since such things could be with some certainty measured. She and the party lacked and lack credibility with the workers and the less privileged demographic whom the Democrats. That has happened because policies have not favored labor.
Republican policies have not either, of course. Had they, the difference would have been far larger. Many of the people who would usually vote Republican did, including most of the racists. People held their noses and voted Trump because they felt that their alternative was Clinton.