Robert M. Gary writes:

BTW: This is a well known allergy. http://www.mayoclinic.com/health/peanut-allergy/DS00710

"Peanut allergy affects approximately 1.5 million people in the United
States. As the most common cause of life-threatening allergic
reactions (anaphylaxis), peanut allergies account for 80 percent of
fatal or near-fatal allergic reactions each year. You can reduce your
risk of having an allergic reaction to peanuts by knowing as much as
you can about peanut allergy and how to avoid peanut-containing
products."

Yes, it's among the most common food allergies, but it's still rare. And
allergic reactions can still be triggered psychogenically as well, especially
among people who have strong allergic reactions of purely physiological
origin.

There's a huge difference between consuming peanut products and having someone
open a bag of peanuts nearby. In the former case it would be easy to avoid
any allergy problems while flying; in the latter case, no place is safe,
including a cockpit.