"Some Roman soldiers had dark skin" and "the show is going too far in their attempts to make it easier for dark-skinned children to identify with the history of the place where they were born" can both be true at the same time. You don't have to be Mary Beard to understand that the former is true, just read the two Cesar books, hardly something only experts in the field do. They are full of examples of foreign units operating on continents far away from home. Centuries later, foreign mercenaries only got more integrated.

This whole story is just right wingers picking the wrong example out of ignorance and then stubbornly using mob tactics to compensate. They can't have a meaningful discussion about the show because they are too narrowminded to understand why the example they picked was the wrong example for the point they were originally trying to make.