IPFS, I'm unfamilar with it - does a gateway have the ability to host anything from IPFS if it's requested to be pinned? Would the hash of the content be the same wherever it is being served? If the service was running could these books have appeared on the gateway?

If yes, it looks like they are sending notices to every gateway they can find assuming that the content could be hosted there as it might or might not and they dont check.

is it a kind of demanding adding something to a blocklist pre-emptively?