And that's exactly the reason why people are total inconsiderate assholes if they claim alergies for something they just dislike. I look with disdain and revulsion at scuh idiots!
Imagine a busy restaurant, Saturday evening, 8:30 and you claim to be alergic to something. The kitchen must pull a five alarm drill in the middle of their busiest time. Make sure that all cutting boards are replaced, for example, everything must be cleaned thoroughly and they must be damn sure that there's no cross contamination whatsoever.
And all because an asshole lied and claimed to be allergic, while in reality she dislikes pineapple.
If you are really allergic to something please, please call ahead and talk with the restaurant, so that they can make appropriate preparations, without having to essentially lock down the kitchen for 15 minutes.
The worst is that people that claim allergies, or gluten intollerance without this being true hurt other people, who really cannot tollerate certain foods.
So your story makes total sense and the place really seems to care. But just imagine the same action in a full blown restaurant kitchen with a number of lines, which all need to be decontaminated during their busiest time.