Yeah whitelist feels like the best option for them and the larger threadiverse community.
I think a whitelist is worse. While it gives them more control, it also essentially shuts out smaller instances and can lead to the existing instances becoming entrenched and hard to replace. I’m also not sure if would be a good move ‘politically’ for the admins. People are going to treat whatever is whitelisted as being endorsed by them.
The main advantage that I see is that they will almost certainly fall out of favor with the majority of the larger threadiverse community. They cannot continue to operate all of the largest communities with a mod team of 4 but seemingly have no plans to change it. They need to be ok with changing their stated relation to the larger threadiverse or they will be doing real damage to the larger community.
Allowing instances to use a whitelist instead of a blacklist is actually a really bad idea. It makes the default not being federated with anything, which makes it far easier to create centralized isolated silos that it’s hard to move off of while staying in contact with, and in general would just destroy the interconnected nature of the fediverse
