Have you never had a guest that you knew was a friend of a sibling, spouse, partner, or parent come over and ask to speak with them? If you did, do you just say one second and then close the door in their face and make them wait outside? If you do that, you are rude. Idk, maybe you are from a different culture than I am, but where I am from, you would be considered rude for not letting a known guest in unless there are extenuating circumstances.