I should know the answer to this because I re-read all the Culture novels last year, but I do think there's some genetic engineering in the Culture. There's the famous sex glands, of course (but maybe the neural net handles part of that too?) and then there's the asocial dude on the remote asteroid in Excession, who I believe was seen as a genetic throwback from the general population.
But it's beside the point, Banks probably included genetic engineering to make sure no-one got horrible diseases and could live to 500 years, not to breed a separate race of elites. And for that he can never be forgiven by these idiots.
Edit both HN and LW comments mention John C Wright, who I have never read and vaguely remembered being a Sad Puppy. He has some dreck where everything is libertarian. Banks was a socialist, but he was foremost a novelist. Faced with the need to create a future society, he naturally designed one with no disease, no material wants, and lots and lots of sex. Who wouldn't? Conservative yanks, that's who.
I follow it on RSS, it's sometime's funny but not required reading.
I don't think you can blame the comic's author for people on HN and elsewhere passing around references to specific comics to make their points.
As to the specific one mentioned here, I don't remember reading it before.
edit to add sometimes it's obvious the entire joke is in the alt-text, like so: https://xkcd.com/3143/