Went through this with late wife. Honor his wishes whatever they might be. Be there for him as much as you can. Let him have what ever he wants either to eat or drink. Let him know you respect his wishes. If he chooses a DNR,don’t refuse him, embrace him. Make sure someone is with him at the end.That’s all I can say.
Yes, I “second” your advice. Let the dear old man have his final say. Love him, honor him, fulfill his requests. Peace and comfort to all at this time.