It’s normal to remove life support from a dead body. There is no guilt associated with that. The problem comes when someone makes a quality of life judgement against another person, and that person loses their life as a result. That puts them in the position of having to either deny what they did or convince everyone else that what they did was right. There is one other choice, to admit they did something wrong. That can be too painful to consider. I can’t imagine the turmoil of having a hand in the death of another person.
Everything you say makes sense. There is a difference between a “live” body and a “dead” body. Obviously machinery can keep certain processes going (for a short while) in a body which is dead (meaning the soul is gone). But if a body is “alive” but needs assistance to remain alive with medical help, it is wrong to remove that help. If a person insists that such help be removed and wants to die, that is another topic.
I have an old friend, I’ve told his story before; who was in a terrible car accident. His wife, from whom he was separated, immediately flew thousands of miles to be by his side. Part of his brain had been severely damaged in a bad car crash. He was on every kind of life support. They wanted her permission to turn it all off. She decided that he should be given a chance (and had to argue and stand her ground); they insisted if he survived (but that he wouldn’t!) he’d be in a coma forever, or if not, he’d be a “vegetable”.
Well, he is now walking, talking, helping around the house, taking care of the garden, and has changed so much that the wife he used to neglect terribly he is now devoted to. He personally told me that he is thankful for the accident because it changed him for the better in his relationship with God and his family. He lost his handsome good looks, much of his strength, and it is harder for him to think and express himself; but he is a wonderful human being who deserved a chance to live instead of being killed because “he would have no quality of life”.
Another old friend was on life support due to different medical problems but his wife insisted that he be properly cared for; he lived to watch his sons grow up, fathered a beautiful daughter, and is a good friend to many, and has some residual health problems.
Some people would have said that both of these men should have had the life support turned off. There was no “chance” for them.