Let’s go simpler: what if your instance was allowed to copy the fed/defed lists from other instances, and use them (alongside simple Boolean logic plus if/then statements) to automatically decide who you’re going to federate/defederate with? That would enable caracoles and fedifams for admins who so desire, but also enable other organically grown relations.

For example. Let’s say that you just joined the federation. And there are three instances that you somewhat trust:

• Alice - it defederates only really problematic instances.
• Bob and Charlie - both are a bit prone to defederate other instances on a whim, but when both defed the same instance it’s usually problematic.

Then you could set up your defederation rules like this:

• if Alice defed it, then defed it too.
• else, if (Bob defed it) and (Charlie defed it), then defed it too.
• else, federate with it.

Of course, that would require distinguishing between manual and automatic fed/defed. You’d be able to use the manual fed/defed from other instances to create your automatic rules, to avoid deadlocks like “Alice is blocking it because Bob is blocking it, and Bob is blocking it because Alice is doing it”.