Peekay4, I believe that the issue of someone disabling these devices can be addressed in a way that satisfies legitimate concerns. Something like the SPOT is so small and low power that backpackers carry them. They are like a cell phone, or a hand held GPS. Aircraft have hundreds of those aboard, none of which can be turned off from the cockpit. So I don't see any need to be able to disable them.
However, for the lunatic fringe, sure, you can turn any EPIRB off- but it will trigger the backups to report an emergency. That's a very simple concept. It should be possible to do whatever is legitimately necessary, but commercial aircraft should never disappear. That's crazy.