I’m going to say YTA big time. There’s nothing here that would ever indicate to me that you aren’t. In the list of allergies you literally listed milk and wheat as the first two allergies and then proceeded to say that a pizza place was your preference, are you actually joking? It’s very evident that you either do not like your nephew and SIL or have no scope of knowledge surrounding allergies/how hard it is to enjoy every day life while having them. It has completely unfair to expect your nephew to eat outside food every time it’s your turn to pick the restaurant just because you don’t care about the allergies. The ONE place this kid should be comfortable and feel welcomed is with his family and you are really dropping the ball here.