Sounds like a typical "but hey, it's free, it's a great way to share something" etc.
So "of course" you are the "weird one" for not participating in this thing. And acting different than the others is a typical warning sign for allistic people that something "is wrong".
After all, if you don't eat the same food/the same way as the others, what is next? You stabbing them in the back?
Btw: I very likely also wouldn't order there, simply because I have my samefoods. Which I can properly digest most of the time, which I am not allergic to, which don't result in a lot of pain.