Celiac is a specific condition, not even an allergy. If someone has celiac, they cannot have gluten without bad consequences. Being able to serve someone with celiac means the kitchen has deliberately chosen to do so and have procedures in place for doing it. Things like changing out gloves, cleaning surfaces or having dedicated space. This also means knowing what cannot be made safe, which often is things like french fries because friers tend to be shared with gluten products.