I agree, in theory, with both of you. I know a little boy with a deathly peanut allergy, and just touching them can send him to the hospital, and smelling them up close can make him very sick.
The thing with the airplane scenario is, unless the plane was totally sanitized from
previous flights there could still be peanut residue, so if a person's allergies are THAT bad they may need to wear some kind of special suit. Most don't have an allergy that bad and just need to avoid actually eating peanuts or being in close proximity to peanuts. For that reason, my friends with the boy with the allergy can't eat at places like restaurants where they serve peanuts and the shells are thrown on the floor.
For a typical peanut allergy (or most allergies) the allergic person just needs to avoid eating them or being very close to them. If someone has such drastic allergies, as described above, it is up to that person (or the family if it is a child) to take extra precautions.
Barbara