This is chutzpah of the first degree. Hillary ran a nasty campaign full of dirty tricks. The Wikileaks release of DNC emails revealed that every allegation Sanders supporters had made was true and then some. Debbie Wasserman Schultz had her thumb on the scale for Hillary. In a lawsuit against the DNC, the defense was that the party doesn’t promise it will be fair.
To say opponents of Hillary are racists is a vicious smear. In fact one main reason she lost is that African American voters did not turn out for her.
This is politics, not hopscotch. Every candidate will provide lots of reasons why all the others are unworthy and try to torpedo their chances. Hillary is more guilty of this than Sanders.