I disagree that this is more convenient/better for privacy.
With the app: the user already has a cell phone, and doesn't need to buy anything else to get protected from falls. No proprietary hardware, just an app to install and he's safe. Plus, he'll always have his phone on him and can call/be called whenever deemed necessary by his caregivers.
There are no privacy implications whatsoever, because the app only reports to the people it is configured to report to - by SMS and Twitter, as well as local audio alerts.
BTW, I built this app for a company that had already developed hardware-based fall detectors, over ten years ago - this is not by any means a new market - which functioned perfectly every time (not needing mmWave) .. and which they determined were not popular because it required extra proprietary/special hardware, which most elderly in this market are suspicious of .. but given the choice to install a Fall Detector on their existing cell phone, which they carry around anyway as a safety net, was a no brainer ..