There's also a limited federation mode that server admins can use. Users and posts are still searchable, but they do not show on the public federated feed.
Useful for this exact case where a server may have beneficial accounts, but the rest should be hidden for moderation reasons.
Still would prefer it being on a proper mastodon server, but I can live with this. Whatever server ends up hosting a President's account now has to deal with record preservation laws for their posts. Let's leave that bureaucratic stuff to threads.