Purely a difference in semantics at that point
Usually people saying that "black people can't be racist" are speaking in wide terms about institutional racism rather than individual or social racism. Obviously a black guy than think that white people are lesser and thus be traditionally racist.
Now whether using that term could be considered intentionally misleading is a whole different conversation but, y'know, whatever
Imo anyone has the potential to be just as "traditionally" racist as anyone else, obviously, but the presence of racism directed towards non-whites has an obviously higher precedent in the west and thus a larger impact