Although, jumping communities/servers might be a bit trickier once the scale grows. And this would be an important aspect from activism perspective.

100% agree. Especially since communities really do "live" on a server. Another server can have a backup of that community's history (IE federated content they see on their own server), but if the original server dies, then so does the that community... and it would have to be re-created.

For example, could make it so that community can’t be deleted, mods can’t take it private, etc.

Fortunately besides deleting all your own content, even mods cannot edit or actually database delete anything but their own content. Even a community delete is just a boolean flag, and communities can be undeleted with no harm done.

But yes there's so much with democratic moderation that has never been tested or implemented, that its completely unpredictable. I'm not sure I would want lemmy to be a test-case for that potential instability, I'd rather have other projects figure out something that works first.