@saxnot The way federation works is that it will only wind up in your local instances if both of the following criteria are met:

1) The instance isnt silenced (this is different than a block, I have no issue with silencing really)

2) someone on your instance follows the person.

Generally people who post garbage will be unfollowed, so generally this wont happen. However in the rare case that it does thats where #1 comes in. Silence, don't ban. Get the best of both worlds.