This is a new form is low. Racist White people are boycotting the new Star Wars movie? Good!

I don't see them complaining about white people playing powerful black colored people in films.

Oh look! It's idiots on the internet! Well, I never!

Were the Ancient Egyptian pharaons black?

They do realize that like 99% of the cast is white.
Attack on white people... in a galaxy far, far away... Dominated by white people.

These people are in the minority and shouldn't be represented in media as if they're the majority.

The hashtag started as a gag from 4chan, which, unsurprisingly was picked up by Stormfront and the SJW crowd. And then, of course, because the media is moronic, they swallowed it hook line and sinker. Great time to be a troll, so it would seem.

They weren't white and we know this because of DNA... and science. And I think their own images.  But the point is that they can play whatever role they want and so can everone else.

I don't think there is a parameter like "race" in the galaxy far, far away. So there is no "attack on white people" or "domination of white people".