Like other admins have recently done, I've taken steps to defederate my instance from Mastodon.art.

A healthy community shouldn't pride itself along the lines of "look, we've defederated, blocked or silenced half of the Fediverse in order to protect our vulnerable users".

A healthy community goes along the lines of "we protect our vulnerable users by promptly and appropriately reacting to any form of abuse against them, with such actions only targeting the abuser/offender, while providing everyone with a safe platform to engage with as many people as possible - because preemptive blocking is always bad no matter what".

You don't protect the vulnerable by creating aseptic void around them. That only creates bubbles, not networks.