If you read the post, it basically boils down to:
- the Lemmy instance crashing
- the primary admin (whom would have system level access, not just admin role assigned in the Lemmy instance itself) hasn't been heard from since last October
sadly it's not uncommon for open source devs and maintainers to "disappear" from the community - a lot of these people do not share what they do with their friends and family, at least not the friends and family that could take over or even take steps in case of their passing. Accidents do happen, so do random events, so it's perfectly possible for such an admin to pass due to some unforeseen reason, and have nobody within their immediate circles who even knew about their role in maintaining the instance.