I agree with most of what has already been said: being elderly alone is not a great excuse for getting to the airport way to late.

However, LX seems to be much stricter than many other airlines when pax miss their flights. A colleague of mine missed an LAX-ZRH flight due to a major traffic jam related to a fire on the road from Las Vegas to LAX (he had calculated a 6 hour buffer into the trip and still missed the flight) and LX just said he lost his ticket and has to buy a new incredibly expensive one-way. And this was the return portion of an F-flight in restricted booking class A. No flat tire rule on LX.