I had a stupid thought about this that I might look into if I'm bored: What if his ability makes it so he can't die from old age? (aka does temperature affect how long someone's body/cells live for?)
In all honesty, raising or lowering temperature even slightly is insanely powerful. Just a few degrees Celsius can be the difference between perfect health and death.
"Worse than a microwave", meanwhile this whole chapter showcased how useful his ability is.
Besides, a microwave is actually a pretty advanced invention, can't look down on it.