Robert M. Gary writes:

He didn't learn about the peanuts until after he broke out. Thiis is
not a rare thing, in fact its very common. If you notice in the story
when you buy cookies there will be a warning label of the factory also
has nuts. Some restaurants also have warning signs.

Mainly because of liability issues. Ten or twenty years ago, it was sulfite
reactions. Every generation has its popular ailments. The only constant
trend is an ever-increasing fear of everything.

But he would react during the preflight, not in flight.

But can he be sure of that? Allergic reactions don't always occur
immediately. What if there is peanut dust in the cockpit, and it doesn't get
really stirred up until air in the cockpit starts moving around after
take-off? Can he take the risk?

It is hard for him to be in public. He wasn't able to go to public
school or ride public transportation later.

Then flying on his own is going to be a real problem. Best not to say
anything about that unless explicitly asked.