Just let these instance owners do what they want ? 🤷 If they want to pre-emptively defederate, that’s fine, let them. There will be instances happy enough to federate with them. Once there’s trouble, they’ll probably defederate.

The great thing about social media, is that you don’t have to reach everybody - you just need to reach your community. If your community isn’t on GAFAM then defederating won’t change the experience.