Taco salad (no chips!). Make up some seasoning packets for him. He browns a pound or two of ground beef, tosses some on top of a bed of lettuce, adds cheese, salsa and a dollop of sour cream. Makes several full meals easily.
Does he GRILL? If so, "burger salads" are great. Since going "bunless" that's what I make. Burger on a bed of lettuce with all my usually toppings.
What about freezing up some stew in advance? Put it into single-serve containers for reheating.
And, like others have said, slow cooking is an easy win.
Life is short: Void the warranty.