Your analogy fails miserably. If your grocery store fails to refrigerate otherwise perfectly good milk, the analogy to the App Store would be that Apple inject

Your analogy fails miserably. If your grocery store fails to refrigerate otherwise perfectly good milk, the analogy to the App Store would be that Apple injected GPL code into the app. No, if Nabisco violates a copyright agreement with the box design of some cookies, and your grocery store sells them (unknowingly), the grocery store is not at fault.