This is 200% the fault of the nut-less girl and her parent.

If your allergies are that severe, you dont belong on a commercial flight. This parent failed her only job.

the passengers are allowed to eat whatever they want. There is zero language in the airline conditions of carriage where it says "allergic restrictions: you cant consume products that are allergic to other passengers".

no rules broken here. Your british tabloids are worse than the US ones 🤣