“I cared for some Old Litvaks in a nursing home. All of them except for one, ate before shacharis. One of them had dementia. If he didn’t eat first, he would start davening maariv.”
You’re proving our point, not hurting it. This is like saying your wife had to be driven to the hospital on Shabbos to give birth, therefore it must be mutar to drive on Shabbos for everyone. This is a perfect example of the idiom: “the exception that proves the rule.”
“Neville, just look in Shulchan Aruch Orech Chaim 666 and 668 and in Mishnah Brurah there also”
OK, not sure why you thought it would change my mind as I’ve learned it before. Addressing the topic of sleeping and even eating foods that wouldn’t normally require a leisheiv basukkah, the MB (and everyone but the Gra) are meikel and seem to confirm the reasoning that you would only be doing these things l’shem mitzvah, whereas eating a meal you might do on an ordinary day anyway. The same logic works for not taking arba minim. If the whole reason for holding l’halacha that you must eat in the Sukkah on Shmini Atzeres hinges on it being normal to eat outside anyway, then it seems perfectly reasonable that that norm could change based on time and location.
There is only one group I’ve ever seen that really treats it like a chiyuv and will even refuse to drink water outside the sukkah on Shmini Atzeres; ironically, that group is Chabad.