Sure, but you're using _their_ free platform to host _your_ content that _may_ be fair use. They have the right to be as legally cautious as they want on stuff

Sure, but you're using _their_ free platform to host _your_ content that _may_ be fair use. They have the right to be as legally cautious as they want on stuff appearing on their platform. You have the right to put your stuff on your own platform without such oversight if you want and directly deal with the legality.