But then you know that. You are simply trying to avoid acknowledging that you are not morally obligated to provide your body to support another person. And you are not morally obligated to continue bodily support once started.
I would never ever start my personal blood donation on the street.
That's insane, in my view. I have no idea whatsoever how I should proceed. Seeking medical health personnal would always be my first step. This is also to protect the other person from potentially flawed decisions I could make, of course. I'm no health professional.
And my point is that the patient does not always get to consent. Unconscious people cannot consent. Infants cannot consent. And that the person providing bodily support is not obligated to provide support, or to continue doing so once support has begun.
you started off with your neighbor. An adult - a consenting adult.
I'm not going to think every single scenario through that you may be going to come up with.
This being said, let's still have a look at your two new scenarios. Maybe, if they are unconscious they will agree with the doctor's decisions afterwards. Infants later agree with their parent's decisions if they survive this. That's what parents are there for. They need to take the best decision's at their children's place.
Three more scenarios and then I will opt out of this debate here. I also have other things to do, Joe.