Another way to look at it is: How would you solve this problem with email?
The reality is, there is no way to solve the problem of moderation across disparate servers without some unified point of contact. With any form of federation, your options are:
close-source the protocol, api, and implementation and have the creator be the final arbiter, either by proxy of code, or by having a back door
Have every instance agree to a singular set of rules/admins
Don't and just let the instances decide where to draw lines.
The reality is, any federated system is gonna have these issues, and as long as the protocol is open, anyone can implement any instance on top of it they want. It would be wonderful to solve this issue "properly", but it's like dealing with encryption. You can't force bad people to play by the rules, and any attempt to do so breaks the fundamental purpose of these systems.
Another way to look at it is: How would you solve this problem with email?
The reality is, there is no way to solve the problem of moderation across disparate servers without some unified point of contact. With any form of federation, your options are:
The reality is, any federated system is gonna have these issues, and as long as the protocol is open, anyone can implement any instance on top of it they want. It would be wonderful to solve this issue "properly", but it's like dealing with encryption. You can't force bad people to play by the rules, and any attempt to do so breaks the fundamental purpose of these systems.