It's more of him complaining of the intrinsic physical characteristics of the actors than the actual content of the film. Talking about how dark a person's skin should be rather than the actual character traits. He has some other identity politics stuff on there too before the physical appearances rant.

I agree. I think he's reading too much into Roberto and not enough into Rahne - Sunspot looks like a walking black hole anyway so his manner of speech is more important than his skin tone - but he's justifiably annoyed if his characters aren't recognisable as his characters.