AIBU to think that if you have invited a friend over at 5.30 am then you should be awake to answer the door to them and not leave them ringing the buzzer for 15 minutes until such time another house mate ends up answering it!
It was 5.31 when I answered the buzzer and it had woken me, I currently have a bad cough and had taken a sleeping tablet so god knows how long the buzzer had been going before it woke me.
AIBU if you messaged someone asking them to come up minutes before then you should be awake and prepared to answer the door!