You could have a system that broadcast on multiple platforms at once. They could for example have a kind of lightweight append only list of broadcast (let’s say something based on ATProto) on their own infra, and appends are replicated to Twitter, Threads, Bluesky, whatever.

In case of issue with one platform at least a place where to broadcast still exists and people can share it, create new copies, share on their own timelines, or other creative alternative ways to share the broadcast.