While you might find a doctor or two here and there who are willing to send patients on mechanical ventilation home, the vast majority of people with emphysema who are put on ventilation live the rest of their lives in an institution. My guess, from the information Jerry is providing, is that his brother-in-law is being sent to the rehab hospital on the ventilator. That is because nothing further can be done for him in a hospital, and in all likelihood, he would die if the ventilator is removed. Which WILL happen, regardless of the family's hope to the contrary.
When an emphysema patient reaches this stage, it is called "end stage" for a reason. It isn't unusual for families to hold out hope for a "recovery" in these instances, especially when the patient has rallied and gotten better in the past. But having to put a patient who has been through what this patient has been through (according to Jerry, that is--2 heart attacks, 24/7 oxygen therapy for a year, double pneumonia infection, and being put on a mechanical respirator without giving his consent and AFTER telling his wife/legal guardian not to do it) in a rehab setting just means the medical folks are assuming that this is the end.
Families, especially spouses, often go through a rationalization--including faith based rationalizations--to justify the medical decisions they are making on behalf of their loved ones. In this case, it sounds to me like Jerry's sister had her husband put on the mechanical ventilator while he was unable to make that decision for himself, after he had told her NOT to put him on a mechanical ventilator.
Once a person in this circumstance is on the ventilator, especially if they aren't "with it" enough to know what is really going on, it is impossible for them to fight it on their own behalf--especially if their loved one isn't willing to let them die.
These are the saddest of cases, IMO. I'm really glad we eventually talked my mom out of going on a mechanical ventilator, and to accept that she was dying and shouldn't use that as a means of prolonging her suffering or ours. I'll always bless her for loving herself and us enough to not make us fight that fight for her.
My father has also been very clear about his wishes regarding mechanical ventilation. But then, he is married to a nurse, who has explained it all very clearly to him. He knows that there is no more "improvement" coming for him. His journey is nearing the end.