I think it’s a complex statement.
Being racist is not limited to one race as we are all human beings who have the ability to love or hate others as individuals. In that sense, yes black people can be racist.
However what they’re talking about is systemic racism which is collective based racism as oppose to individual racism. The dominant group has the wealth and as a result, everything falls within their interpretation of how society should be governed based on their frame of references. In that sense, Black people are not in a position to be racist.