My 2 year old has a severe peanut allergy that caused him to go into anaphylactic shock the first time he ate peanut butter. It was the worst day of my life. "Managing his allergy" actually DOES include requesting that people do not eat his allergen near him for the length of a flight. That is one of the MULTIPLE precautions I take. I also make sure that I bring food for him that does not contain his allergen or have risk of cross contamination. I also wipe down the seats, arm rest, and tray table thoroughly before he sits down, I have oral antihistamines and his epipens an arm's length away from me at all times. But epipens and antihistamines are not 100% effective, and it is impossible to receive emergency medical treatment when you are stuck up in the air.
Nothing is stopping you from eating your nuts once you're on the ground, by the way.