I've heard from a lot of teachers whove told me that apparently this is not unusual in school settings.

If a student has a severe nut allergy, nuts are banned.

This actually seems reasonable to me in a school setting. For once thing, since everybody knows about the ban, they can plan around it.

And unlike a plane trip, school is every day and it's required.

I don't think it's fair to isolate a kid under those circumstances.