This ignores something fundamental. Allowing for seats to be cleaned before chances great but what happens if somebody opens a big bag of nuts while sat next to somebody with a severe allergy and proceeds to eat messily? Also, my wife, who has a severe nut allergy reacts to the smell but in this case if the person refuses to stop I’d just say to her “go ahead, throw up all over them, they’ll soon stop eating nuts” 😂 https://www.bbc.co.uk/news/articles/c2dpkpjjnw2o