I'm allergic to shrimp and crab. I don't order sushi, Tacos, surf and turf, pasta dishes that contain shrimp and or crab and make a big scene about it "I want this but hold the shrimp/crab, I'm highly allergic!"
I also don't go to restaurants that I know cross contaminate. Like long John silver's. I think they cook everything in the same grease but I've had reactions to their hush puppies and their fries.
If you're going to make that much of a fuss, just eat at home, or take the easier route and order something that's not complicated. Like every Chinese restaurant has shrimp fried rice. I've never been sick/cross contaminated and I've never brought it up to them.
shyt happens, if this is how he reacts or how he chooses to react everytime shyt happens there's only one way to permanently fix him, and it's not through diversity training.