Natural death didn’t used to include IV’s and medical intervention for people who have no hope for recovery. That makes it different from Terri Schiavo.
My father died of an inoperable Glioblastoma IV. It had taken over most of his frontal lobe and rendered him blind and unable to speak. He was a vibrant man, a triathlete at 77 and he had a living will. The cancer made him unable to eat or drink. He would not wanted to live that way or prolong his life in the hell that tumor wrecked on him.
Everyone’s situation is different. Broad brushes do no one favors.
Terri was only receiving food and water by feeding tube. She was receiving no other life sustaining treatment and would not have died if it weren't for the removal of her food and water.
I suspect this case is very similar. He has Lewy Body Dementia which makes it difficult for him to swallow. If not for the removal of hydration by feeding tube he most likely would not be at immediate risk of death. Sepsis is dangerous but usually treatable, as are bed sores.