Some people's attitude toward this is a joke. I love how there are so many alpha keyboard warrior responses to this simple request. I can't believe that a request to minimise the risk of someone getting seriously ill in a confined, pressurised space, would be dismissed by so many of you in here.
Let's turn it around a bit. What if one of your loved one's was the reason for the request? Would you still crack open that bag of peanuts and start munching away? Yeah, I don't think you would in all honesty. So why should there be a difference just because you don't know the other person? Would you really willingly endanger them by ignoring the request?
I also find it utterly ridiculous that people say he shouldn't be flying. What should he do? At the end of the day, is it really such an inconvenience to not eat a bag of bloody nuts until the plane lands again?
I don't know anyone with a nut allergy, but I know that they can be pretty nasty. It's so easy to transmit airborne viruses on a plane with the air being recirculated so much, so it would seem reasonable that other particles can trigger allergies and such as well. It isn't their fault that they have such an allergy, and I actually can't believe that people would risk their health just so that they can have a little snack. Utterly selfish in my opinion. No wonder the world is in such a sorry state.