"...I have little sympathy for this passenger or the other people mentioned..."
oldsicilian- If one has medical issues, pre planning wont work.
Bottom Line: As best you can, make arrangements before there is an emergency.
First, if you have a medical issue, do your research before you travel. Understand the restrictions you may face and how they may impact you.
Second, do what you can to mitigate the risk of an incident, talk to your doctor. This may include wearing Depends or other garments to mitigate soiling your clothes.
Third, talk to the airline beforehand. As you board, talk to the cabin crew, let them know what is going on. Prior communication with the right person can prevent misunderstandings.
Most of the incidents we hear about are at least partially about miscommunication. Passengers must also understand that once on board, and the doors are closed, they can't simply move about the cabin.