Why are they just now trying to get a ping from her implant? And why are they telling the public?
I'd go the Walmart path...I now think that everything was from Walmart. An FBI geek knows how to attack this. A Walmart employee....in your dreams.
Last point first. People saw something hanging off the bottom of the helicopter and concluded it was a frequency sniffer. It is likely it is not just a bluetooth sniffer but can sniff a wide range of frequencies.
The main job of a pacemaker is to keep the patient alive and not continually trying to report back to the relay device and drain the battery prematurely. The pacemaker isn't going to constantly try to ping the reporting device if out of range. It works the other way around. The pacemaker is in listening mode and responds when pinged.
Take for instance of a BLE(Bluetooth Low Energy)key fob. The key fob isn't constantly sending out requests as to where the car is. It is the other way around.