I guarantee you white supremacists are overjoyed by Mr. Trump’s spreading their favorite talking point.
In case it isn’t dizzyingly obvious:
1) white-on-black crimes provoke outrage when they are motivated by racial animus or they are part of a pattern of violence committed by those in power (the police, for example) toward black people.
2) Unlike 1), black-on-white crimes cited by people throwing out this B.S. argument are virtually never motivated by racial animus. The criminal happens to be black and the victim white.
3) hate crimes (crimes motivated by racial or ethnic animus) committed by blacks against whites are every bit as prosecutable–and are prosecuted–as hate crimes committed by whites against blacks. They just don’t happen as often and aren’t attached to hundreds of years of white racist violence, slavery, genocide, and notorious hate organizations (KKK, neo-Nazis, etc.).
The way Dylann Roof became brainwashed into slaughtering nine people during a Bible study at Emanuel African Methodist Episcopal Church was by immersing himself in racist Internet propaganda about “black-on-white crime”.
Now our thug president is circulating exactly the same propaganda.