Ultimately it’s his instance, his liability if shit goes sideways, so his call to make.
I don’t think it’s the end of democratic anything, and it seems to be more because another instance took action and defederated than the call of a single person, because context matters.
The statement referenced said there was no responsive administration at rammy as reported by a rammy user and attempts to reach admins by others were not successful.
That’s very different from what you’re trying to claim.
Another vote for this series. Cherryh’s books are some of my favorites!