I think this was a planned post she wrote while dealing with her disease, and likely a family member added in some relevant details and posted it. I've had a few terminally ill family friends that want to reclaim some control in death what life had taken from them, so they plan their funeral and some post death things out ahead of time.
Yeah there's no way it's worth it for an obituary. You need it out in good time, so you can't have a delay longer than a few days. But it's definitely possible to be knocked out (or in a no-signal zone) for a few days and survive.