I find it semi-funny in a book separating people by color you ask about skin color though lmao. It don't be mattering homie!
I mean, I don't even agree with the comment you're replying to (because I think the majority of the cast being white can be logically explained) but it is still valid to care about racial representation in a book about seperation by Color. This is written for a modern day audience that still lives in a world with a lot of racial tension. Lack of representation in media is a real problem and no diversity CAN suggest bias by the author. It is not ridiculous to bring this topic up. Yes sure, in this universe skin color doesn't matter, but it does matter why the author chose to write it as mostly white.
Before anyone tries to burn me at the stake: I believe there is a good explanation for why they are majority white. The original Golds were part of the ruling class and today the upper class/the richest people in the world are mostly white. And since there is no mixing with the other Colors they would have almost the demographics as 700 years ago.