Even if he chose a lock box with instructions with what to do in case of god forbid something were to happen. He still has over a decade or so to go before retirement, depending what he does, some places early retirement can and does happen.
Most people have directives regarding organ donations and resuscitation directives, knowing there's an envelope with instructions is a small thing in reality. How often does the unthinkable happen? Quite often. My late stepdads father, within a year of buying a new home out of state to move his wife back to her homestate collapsed with a heart attackm. They had just bought their camper for retirement traveling. Things do happen, quite tragically too. My mom became ill soon after her early retirement. She was 55.

Maybe let him know that you don't want him not here but with your own struggles to be less dependent this stuff makes it difficult to not worry about.