Nothing like junk food science.

Bottom line: aspertame contains small amounts of methanol,

Another bottom line: if you have a serious allergy to aspartame, you know it
before you grow up, go all the way through pilot training, and become an
airline transport pilot.

Why not ban peanuts too, in case you've grown up in another galaxy till the
minute Northwest hired you and offered you a bag of snacks that'll turn out to
kill you?

Honestly. A pilot reckless enough to take control and slam a diet Coke knowing
he has a disabling allergy to the sweetener will have disqualified himself from
professional employment a long time before he slugs down a beverage that'll
knock him out in the cockpit.