You can immediately see who is an admin and who is not.

If you have an open instance and someone puts csam on it and reports you, you’re toast. Thats what blocklists are for and they arent new. Mastodon instances already have blocklists which every sane admin uses. They even come in different flavors.

The way this works is that certain instances „vote“ on blocks by applying blocks to certain instances and if one, multiple or all „trusted“ insrances block an address, it „federates“ through these updated lists.