Nut Allergy on the plane

I have every sympathy for those with nut allergies and understand how very dangerous, in fact fatal, that this lack of immunity can be.
We were travelling back from Tenerife and were told that no nut products would be served on the plane due to a passenger having a nut allergy. We were told not to eat any of our own products with nuts. (This has happened about four times in our travels to and fro.)
Of course we complied but half-way to the UK someone started eating a packet of nuts behind the person with the allergy. This called a big upset although handled beautifully by the stewardesses.
My question is that should the person with the allergy wear a mask and would that be effective? My daughter developed flu in Thailand last year and even though eventually recovering and cleared for flying, she had to wear a mask all the way home. The other passengers didn't have to wear masks so that she could be without. It seems to me fair that the unfortunate person with the condition should take their own precautions, or is this a bit unkind?
Some products such as chocolate have small quantities of nut oil added so items appearing safe may not be.

I don't think it's unreasonable to expect people with allergies to wear a mask, it would cut down the chances of a bad reaction.

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Wow I'm glad I saw this, I'd not thought about that at all. We fly in 8 weeks & I was planning on making a bumper load of peanut butter & jam sandwiches as (other than chocolate spread) it's the only sandwich filling both my older kids will happily & consistently eat. Guess I need to rethink that.

I do think it's annoying for everyone else, that said I wouldn't want to inadvertently harm another passenger.

I'm not sure if a mask would protect a nut allergy sufferer. I'm not really sure how sensitive they are to the allergen in the air and recycled aeroplane air.

First time I saw here that there is also exit nut allergies. For any type of allergy we have to be very care full. I think to wear a mask to avoid the allergy is more effective.