Thread drift?
I wonder whether our concern for people with medical conditions has got us away from the original point. Sure you can keep important documents and medications on your person if you think ahead. My point originally was that if the overhead lockers were centrally locked, would this certain knowledge have a positive effect on SLF behaviour? Is it worth trying?
Coupled perhaps with an announcement 'Those who wish to take hand luggage with them should remain seated until all other passengers have left the aircraft'.