This is what I have seen in working with the elderly and doctor's in these types of cases. Doctor's have been trained to treat and to cure. They will never say "You know I don't think that your life is worth trying to save since you are so old" . If he is going to a Dr. they are assuming that he is requesting their services for such. Usually doctor's assume that we will tell them when 'enough is enough' and then at that point will start palliative care. If he is still able to make his own decisions, he needs to tell them his wishes. Otherwise his power of attorney can speak for him. His primary doctor will then order hospice care. Hospice nurses and doctors will treat discomforts that come from disease and end of life changes, but the goal is not to cure or prolong life.
I see this situation often, and it is very sad to put people through treatments and suffering when they truly are ready to go with their creator. Someone needs to say this in words.
Hope this helps.