If you have any trouble multiple that by 1000. That's what your asking him to do.
PLUS, FiL's eyesight isn't as good as it could be, because he has cataracts but refuses to get surgery for them. *My* Dad was ecstatic to get cataract surgery, because for the first time in his life he didn't need glasses (though he soon realized he needed readers, which was a weird experience for him). I have no idea why FiL refuses to get cataract surgery, but he won't do it, so he's having more and more trouble reading things and, well, *seeing* things.
It really is a recipe for a broken leg or hip, and THEN how in the hell do we get him back to Ohio? This is such a bad idea. And more than bad, it's just mean.
I suspect it all comes from SiL, actually. Her mother has dementia that is so bad she doesn't recognize anyone, and she lives very comfortably and happily in a care facility. About 12 years ago, as her mother's dementia was developing -- but she still knew all her family, was oriented to the day/month/year, etc. -- SiL decided they should take her to the beach. [See a theme?] And her mother was very agitated about it and didn't want to go, because she didn't want to be out of familiar surroundings. But what SiL did was show up the day they were leaving, and pack a bag, and cheerfully tell her mother "Oh, you've been looking forward to this; let's go!"
I also think *that* is a shitty thing to do to someone with dementia, but -- it was her mother, and before my time, so whatever. But I think that SiL is trying the same damn tactic with FiL. Except that he doesn't have the kind of dementia where she can just breeze in and cheerfully tell him he's been looking forward to this, pack his bag for him, and force him into the car. He has enough of his wits about him to know that's total bullshit.
Okay, so I secretly want him to just tell BiL and SiL to take a flying leap and leave him alone. He won't actually say anything like that, but when push comes to shove, I think he'll just Bartelby his way out of it. I hope.