They demand the airlines follow their request, no matter how much it inconveniences the airline or other passengers.
My daughter is allergic to all tree nuts - to the point of hospitalization when exposed (at times accidentally). We ALWAYS carry epi-pens and Benadryl - and fly everywhere. Has never been a problem with nuts, and she’s never had a reaction on a plane.
Is she allergic to peanuts too? My SiL is severely allergic to peanuts but not to tree nuts. Peanuts are not actually nuts, they are legumes.