Mental capability to comprehend the responsibilities associated with these exits is not something that can just affect the elderly.
At some airlines you can sit by the self help exit at 14. Not many of them listen to the briefing given to their parents who could be incapacitated should an incident occur. I doubt that many 14 year olds have the maturity to grasp their potential responsibilities here.
One of the most sensitive situations I have had to deal with here was when a newbie CC who was manning this exit on boarding came to me and said she had " a retard at the overwings" and could I sort it out?? Her remarks were just
!!!. Her lack of empathy and sensitivity was
Closer inspection revealed that a party of 6 had boarded with speedy boarding and made a beeline for these exits. One of them had learning difficulties. This chap was certainly physically capable of handling this exit and was in his early 20's so met the age criteria.
To cut a long story short I moved him and a companion for take off/landing. He sat in these seats for the cruise so everyone was happy and discretion maintained. This was a full flight and other pax had empathy and were happy to oblige.
The CC concerned earned herself a chat on disability awareness
As for SpB refunds well I note any moves in the interests of safety on my FER. What happens after that I have no idea..