Or perhaps it's the reverse. If you ask "white men" about the liberation status of women/minorities, you're probably going to find them MORE likely to say that equality has already been achieved. So when they write stories, they'll write them as if everyone is equal and living the same utopian dream they are.

On the other hand if someone comes from a background where they feel oppressed, they're going to write that into their work.

That's part of the point of the article. People continue to extrapolate from what they view culture currently is, as if it continues indefinitely into the future. I think based on that "white men" are going to view it as being more pleasant and fair (i.e. their own experience) than minorities.