Brain stem death is not the same as being in a minimally aware coma. The most primal reflexes including those that stimulate breathing and the blink reflex are gone and there is no chance of recovery. There are no electrical brainwaves, associated with thought. Being entirely dependent on life support for the most basic bodily functions is not life.
Preventing an inevitable cardiac arrest in someone who has already died is wrong. There are hospitals in London where dead relatives of the very rich, often from the middle east, are suspended in perpetuity because of a failure to accept the inevitable and because it pays extremely well. I resigned a good job rather than get involved in that amoral "care" when the hospital decided to chase the business.