Very hypothetical there, like you're reaching for things that could go wrong.
I know that centralisation doesn't work because I've seen it turn the internet to shit over the last 15 years. If I had it my way we'd go back to small independent forums with no federation because they were much better communities. But in the name of progress, federation does have some advantages, but as soon as things start getting too big there should absolutely be defederation to prevent the platform from getting like Reddit.
im telling you things that are happening right not to various instances for various reasons, all of them down to the personal bias of the admins, not the consensus of the users in that instance.
You fundamentally so not understand the problem with federation and the admins. Is not a good thing just because it is, it's the same problem, in a different coat.
To be honest, if that person is so keen on centralized platform, why are they even here? They should just go back to Reddit, they might come back here later