So I'm not in favor of this admin or this as a requirement by any means - but in theory it could be a good idea.
Keep in mind how technology works. Models today might be a separate bracelet, but there's no reason you couldn't just have the RF chip built into your wrist watch. Or a belt buckle, a shirt button... Don't know about you but I always wear a watch, only take it off for shower etc.
RFID devices only need to be within range to work, and you could fix the range to say 6'.
Technically this opens up a whole new supply/demand realm of RF integration into existing things.
And if it is just built in subtly - no thief would know what to steal with the gun.
The biggest hurdle IMO is that it has to work 100.00% of the time. First time somebody is unable to use their weapon in self defense b/c of being locked out, and gets overtaken there will be hell to pay.