They're not banning anything. They're banning it from their platform. They don't get to say "You can't publish that", but they do get to say "You can't publish that in collaboration with us". There is nothing stopping the author of this work to raise funds via alternate means, which is much as it has always been. I imagine most all controversial works have had problems getting published, but I don't think people cry out "censorship" whenever a publisher rejects a work on vaguely moral grounds.