I made the comment wondering about mental decline. It is definitely something to consider, given his friends have said his health was declining recently, and that in some cases, mental decline can happen as you age. Is that being ageist, or realising it could be a possibility, given what we know? Regardless, I own the comment and stand by it.
As for the apparent lack of regular (weekly, if not more often) outside help, I get that too. In my experience, elderly people can (again, not always) be set in their ways and want to continue their life the way they have created it. It can be hard to admit you're not the strong, fit, capable person you used to be. In this scenario, where we have 2 people who liked to live a quiet life and were treated just like locals in their town, and yet are wildly famous, this can be harder to accept help in any form. Whilst many, many famous people have staff to do any and all ridiculous things for them, some shy away from that. As a famous person, it would be hard to trust anyone to come into your home, your sanctuary. As a frail, elderly person, I would imagine that to be immensely harder still. You can also imagine that when his time came, he may want to have been remembered as the actor he was in his prime, and his huge catalogue of movies. Allowing staff (like a cleaner) into personal areas of their home would open them up to the potential of being used for monetary gain if an unscrupulous person were to sell photos or their story.
Again, just speculation and my opinions only. No facts, no sources.
