if you are seriously worried about the same thing happening to you, just have Apple cut the string and carry the bag out by grabbing the whole top of the bag.
i am just going to omit the bag period anyway and carry the box out, and the phone in my pocket. if someone wants to try and take the empty box, let them.
i also CWFL and would never have anything that could tie my hands up wrapped around them in case SHTF...