I got exempted from my university's required meal plan by having my RD write a letter to the school's Disability Services. That was for anorexia, because I felt so unsafe eating dining hall food/food prepared by others that it was much easier for me to eat enough when preparing my own food. I'm honestly flabbergasted that they won't let you exempt when their food could literally make you sick??? This doesn't even sound like an ED issue, if even the allergen-free station might not be allergen-free--that's so fucked up and dangerous.

If you can afford it, maybe try to see a non-university-affiliated healthcare provider to vouch for you. Or see if your school has a disability advocacy group that can help on your behalf. So sorry you have to deal with this, and good luck! <3