It's straightforward. Reactionaries can't and/or won't process the nuance of circumstance that distinguish the traditionally oppressed group from the privileged. So, to use an example from another magisteria, they get angry that:

-People of color playing English dukes and duchesses in period dramas is considered interesting, but that:

-People of European origin playing black stereotypes in blackface is considered racist.

They don't see the possibility of a future world where a white man could play a historically black role, because that future is contingent on the extinction of institutional and personal racism. So they just get mad at the anisotropy that they themselves encourage in the environment.