My observation is that at 93 he is still mobile, still mentally sharp, but he is losing his strength. At this point he still finds things to entertain him, but he is basically waiting to die.
So we have established that if you keel over dead, you’d be lucky. But if there is a chance to deteriorate enough to need assisted living and you don’t plan on killing yourself, moving into a facility that offers assisted living woukd be a wise choice, because you can chose where to go. If you refuse and end up being caught by surprise, then based on lack of availability, you might not end up were you’d prefer to be. He has decided to take that chance.
Finally, on the topic of assisted suicide, it might be an easy choice if you were losing mental acuity or becoming bed ridden. My father’s side of the family makes it into their 100s. Both my Great Uncle and my Grandmother (she got leukemia) ended up in the being bed ridden scenario for a period of months. If I am to find myself in such a circumstance and assisted suicide was an option, I’d seriously consider it.