It could work if you are guaranteed to be at home and no doubt you get a text when the drone turns up... so essentially it will work if you are at home and only if you are at home.
Loads of delivery services just leave packages without signatures, even in the lobbies of large apartment buildings.
However, the point of this service seems to be getting an item within an hour, so you would only order with that option when you really needed it. But for those that are worried, maybe there's a chimney-drop option?