AITA for refusing to give a cupcake to a child because he is allergic to one of the ingredients and his mother is a known liar?

My niece (17F) baked a large batch of cupcakes for her school bake sale. She spent most of yesterday making them and had a little trouble with the frosting as the butter was a bit warm and on the verge of melting so it was difficult to get it right. It took her a few tries to get it and I think it turned out pretty good (there may have been a few cupcakes that were sacrificed in the process). She took the cupcakes to school today and word must have gotten around quickly because she had sold most of them by the time I dropped her off this morning and was sold out a few minutes before she started school.<br><br><br>Before we left I ran into one of my friends who I hadn't seen in a while and her son. He was asking my niece if she had any baked goods left and she told him that they were all gone. Since I assumed he was sad that he had missed out on the cupcakes, I figured my niece would be happy to give one of the "sacrifices" to him so I told her to go get one for him. As soon as I did my niece started being weird and hesitant about it and my friend jumped in and said that he was allergic to dairy and that the "sacrifice" cupcake would be out.<br><br><br>Now for the problem. When we got home my niece asked me why I tried to give a cupcake to a boy who was allergic to one of the main ingredients. I reminded her that he was allergic to dairy and that is why she couldn't give it to him. She corrected me and said that he is actually allergic to almonds and that she specifically bought a certain brand of almond extract because it was almond free for this reason. I was confused about how he could be allergic to almonds when I specifically heard her and her friend say that he was allergic to dairy so I asked my niece about it. She said that he is not allergic to dairy, but his mother will often say that he is to get him free stuff. She said that his mother is notorious for this and since she knows that I don't keep almond extract with real almonds in the house she figured that the "sacrifice" cupcake would be fine for him. I am now wondering if I was an asshole for offering the cupcake when I thought he was allergic to an ingredient in them.<br><br><br>ETA: I say "sacrifice" cupcake because we did eat it, just as a loaf of bread. It wasn't wasted.