Crazy allergy policy or AIBU?

[Smarshian]

Booked a party for DD. All good. Friend has significant food allergies and usually brings her own.
Called the centre to inform and they have introduced a new policy that no food can be brought in from outside. No exceptions. They can’t cater for her (I don’t think - although am checking), and mum would rather she brought her own as safer for her.
I queried the policy and they said it was to stop cross contamination to others. They had had an incident and updated policy. Assume it was a child who had eaten nuts on the premises and had a reaction from what I was told.
This means if we can’t find anything that mum and child are comfortable with that she will have to sit and watch all the friends eat without her.
surely this policy hurts the allergy sufferers more?!
Ridiculous policy or AIBU?

The logic of trying to ensure the safety of other children falls apart though. We had this at more than one soft play where they would not cater for allergies, would not allow us to bring our own sandwich, but were fine with any birthday cake brought in.

Children with allergies will learn many times over that they are different and need to live differently. They don’t need to sit and watch everyone else eat at a party as some sort of additional life lesson.