There are some points in the Pemi where reportedly some folks get cell coverage. I don't track it but seem to remember that my friend had cell signal at Diamond Ledge. I seriously doubt that a PLB ping would get S&R in place fast enough to make a difference in a medical emergency but lacking details on this incident its all speculation. There was a recent rescue where F&G reported that they responded with carrying in necessary medical gear to a person in the backcountry but how they knew to do so was not called out. PLB pings do have some inertia in their response, last thing I knew the satellite coverage could introduce up to 3 hours of delay. When a legit signal is received and verified, the contact has to be verified by attempting contact with the emergency contact named in the registration and then handed off to the local contact that coordinates the rescue. The rescue coordinator then has to decide what type of rescue is required as all they have is a ping at a hopefully accurate location if the PLB signal was not impacted by terrain or operator error (RE Kate M's issues). At best S&R will make an initial response on foot with basic first aid skills and gear and then call in more advanced care. This lack of message ability for PLB is frequently given as justification for a Spot type unit which is debate for another day and thread.
I believe F&G does a very detailed post rescue analysis with the participating parties but the general public is not given access to it. Perhaps someone could attempt a FOIA request? In general I believe F&G and other rescue organizations are trying to emphasize that PLBs and Spots do not guarantee instant response in the backcountry, at best they speed things up but a hiker should be equipped and expect that rescue may be many hours, overnight or even a day before help may arrive.