Corrosion is only active above freezing and accelerates as the temperature rises.
The reason he is seeing rust on the tips in winter is because of the heat of the exhaust.
Any properly maintained car will see very little rust. I sold a 2000 Camaro last fall that I drove for 12 years in the winter as my daily driver. It showed very little rust and it was mostly metal.
Why should you save a car for the next guy. It's your car to enjoy how you wish.