I have a read only temperature sensor in my old-school non-computerized refrigerator and freezer. Hack until the cows come home but it still can't turn off my freezer.

Good. You've got a read-only widget that monitors your freezer.

If it were hacked to start delivering temperature readings that were dangerously-high while you were out of town, then: Would you keep the food, or discard it?

Off topic but "hack until the cows come home" put a smile on my face.