That's part of the zero tolerance mentality. Means people don't have to think, choose, or make rational decisions...
Having had a major histamine reaction just short of fullblown anaphyletic shock last week, I can say schools should have the wherewithall to deal with them, though.
For some people, touching the hand of someone who touched peanuts is enough to induce shock. For others, eating nuts is an excellent food choice that prevents things like gall stones and gives you hight quality fats that your body needs.
I think banning nuts is an exagerated response, but people with potentially severe allergies do need to be remembered. What happens, though, if the response is to ban...you ban dairy, rubber, nuts, and so on and so on. It's not necessarily the most sensible method.
Speaking of nut products, I found an interesting label on my peanut butter. It listed the ingredients as blanched peanuts followed by a statement that the product was made in a plant that uses peanut and nut products.