non-skittish hosting providers are uniformly also unprincipled

Yeah, this is what I'm saying (although absolute free speech is itself a principle). I wish it weren't so, but you're 99% right that the cloud isn't really usable for anything outside the Overton window, whether it's far left, far right, erotica, pro-suicide, extreme trolling, etc.

However if you're using Cloudflare you can "hide" your backend hosting provider and they usually won't kick you out because they don't take any reputation hit. So I still suspect a mainstream cloud (with good off-cloud backups) could work for AO3.