My mother had the same argument, and my husband agreed with it. I told them both that if the only things keeping me alive were food and water (like right now), they'd better not decide that I don't need 'em.
By those standards, since oxygen in the air is keeping you alive as well, anyone on a ventilator is not on artificial life support, and should never be disconnected. Air, food and water are not artifical life support, but the mechanism of delivery may be.