do you really think these basic and honest emotions are so elaborate? are an actual plan of what we want to do next, and how everything should be handled? You can make it as confusing as you want, search the grayer areas, etc...
Some things i can answer a bit, if you have religious reservations about it, good for you, make a will where you stipulate what you want and don't enforce it on the rest of society.
But in general, he's fucking angry at people who are saying he should let his father suffer, and won't let him do what he and his family think is the most humane thing. I would be too. And i would wish similar dire things on such people. That doesn't mean i will act on them, there are luckily laws preventing this, our society won't allow this. But that doesn't mean that's not what i would feel, think and even at the moment self say. Give it a few weeks to come to a more rational, civilized point of view.
And what is the more civilized answer? stop pushing your life choices on others, if you want to live like a plant, or suffer and be kept alive even if you will never heal, good for you, but i don't want that (and I'm happy i live in Europe where this is allowed).