Short answer: there are 2 admins, one of them went missing, and they have the keys to restart the server.

The other admin is actively working on getting a new server online and will redirect the old domain to it.

Probably won't be long now.

Is it November already?

https://piefed.zip/c/fediverse/p/1084529/lemmynsfw-is-down-possibly-forever-the-server-is-still-serving-images-and-videos-though-if