Looks like Mark also had an unarmed roommate that was a bit too anxious to run in front of a muzzle to get a peek at the fleeing would-be home invaders.
I noticed the roommate as well running out in front of his friend with the AR between him and the bad guys. If they had returned to fight he was in a cross fire.
I always tell my wife and kids, if you hear tell you take cover and me grab my weapon, you go to the master bedroom, lock the door, call the police, arm yourself and stay put until I come back from the disturbance. Do NOT follow me, especially coming up from behind me, it is an easy way to get shot accidentally. I will come and get you and if it isn’t me or a clearly identifiable law enforcement officer you shoot to kill if anyone burst through that door.