It is perpetually surprising to me how much other people feel it's their business what other people choose to eat.
Food's a social thing. Placing nonsense limitations on what's allowed can really cramp social settings.
The test for celiac requires a person to have been eating regular amounts of gluten for 3 months before the test is done. When my wife is in a position such that a crumb of normal bread in her meal can cause her pain afterwards, there is no way she can eat gluten for 3 months in order to get a diagnosis by a doctor. The best she can get now is a statement that she is sensitive to gluten - but that sensitivity is enough that she can't have food cooked in the same pan as your food when you don't give any consideration to her.
So don't say this is "bullshit food intolerances" - just because you don't have to deal with it does not mean that it is not real.
I avoid wheat products given the choice, but I won't stop eating wheat products as A) I like them, B) I don't want to be one of the whiny "I can't eat this" crowd (who also seem to come out with crap like dust allergies, or smoke allergies - everyone sneezes at those).
There is absolutely a third option between "Coeliac" and "can eat gluten without any unsavory symptoms". Even a doctor may be unable to diagnose Coeliac disease via blood test but able to diagnose a sensitivity to gluten (via similar tests) that has a different cause (Coeliac is not the only explanation).
I understand the frustration of dealing with people who are self-diagnosed (it's unreliable, and comes with its own host of caveats and questions), but I'd refrain from drawing conclusions like this without actually knowing the person's history.
Suddenly something as simple as ordering a dozen cheese and a dozen pepperoni pizzas the morning of the party turns into a multi-day consensus finding exercise and after the histrionics, sensitivity meetings with H.R. and shouting subsides you end up with a catered meal provided by a specialty diet catering company that nobody who would have just eaten the pizza will touch, doesn't taste very good and it costs 5 times as much and now thousands of dollars in wasted time is the result.