GRR Martin actually doesn't represent it. There are plenty of POC in his writing, and plenty of people with undefined skinstones that could be whatever the reader wants them to be. However, the loudest GRRM fans (specifically, those who run the official website, and there are entire sites and tumblrs devoted to being against them), are racist and sexist, and throw a fit whenever anyone even hints at the fact that a character in that fandom might not be pale-skinned.