I was shocked to realize that Americans (I guess) consider this universe particularly "gay". It is just a civ where sex is dedramatized and LGBTQ is considered like it should be: just as a set of preference in that simple facet of life. I mean, even the pretty conservative Heinlein describes futuristic universes where being gay is nothing weird.
I see your point because I also don't think it is necessarily particularly "gay". However, I think The Culture is always mentioned in reference to the FALGSC meme because it is one of the best examples in fiction of such a thing. And with respect to that, I view the adjective "gay" in said context as more-or-less just meaning "not influenced by cishet supremacist thought". Just my opinion though and your mileage may vary!
I agree and understand it, just wanted to say that it is as weird to me to call it "gay" because it is not homophobic as it would be to call something "black" because it is not racist.