Unfortunately I don't have one in front of me right now to test.
But first, the little lock tab can crack after extended use:
https://www.tetongravity.com/forums/showthread.php/328404-Pieps-DSP-Pro-broken-switch
Doesn't seem possible though from a single impact if the beacon is worn properly, i.e., facing in toward the body.
Second, if the beacon is worn improperly, facing out, the switch can move inadvertently:
But of course all sorts of other problems can happen with all sorts of other devices if used improperly!
Third, if you press your thumb against the locking tab and use your other hand to move the switch:
... well, right, of course that moves the switch, that's exactly how it's designed to work!
For that to happen in an actual incident, something on the user's body would have to press in sharply enough to depress the locking tab.
And simultaneously, the switch would have to be moved by ... well, in the video, the user simply reaches in under the harness and moves the switch.
I see claims that over time the switch mechanism can loosely up from lots of use. Perhaps that's the little lock tab no longer having enough force?
If so, I would like to see a video attempting to simulate how this can happen with the beacon worn properly, like this: