If I had an incapacitated child I would jump at the chance to keep him/ her small (a manageable weight to life, carry, transport). That way I would never have to give him/her over to someone else's care as I age and got weaker, I could still hold and carry him/her, bring him/her out more, bathe, clothe, change... everything would be easier (and by "easier" I mean "not impossible," as it would be impossible for me to carry/lift/transport a full-sized adult male or female without a lot of mechanical or human help).
When my daughter was in ICU there were two vegetative kids across the room from her. One the mom had put in a group home because she couldn't care for him anymore. He was a teenager and would have been too big for me to hold or pick up without the help of at least 2 other people. The other was also big, but he lived at home with his grandma, but basically these two kids just lay flat in bed all day. If they had been small they could have been held, rocked, carried, easily placed in a chair for a walk.
I would definitely do this if I had a severely brain-damaged child. It's a brilliant idea that will help keep the child closer to home and the parents less in need of strangers for her care. I'm surprised the parents were vilified. All I can say about this world, is that people sure like to judge and throw the first stone.
<------- the guests who keep visiting this forum, yet somehow they don't register an account.