I agree that's why Brian did not go outside, Wishbone. But a few details in our answer are wrong. There are so many people to keep track of!
It was Brian's sister-in-law on the other side, his wife's sister Jennifer McCabe, who woke Brian and Nicole up by coming into their bedroom to tell them police wanted to speak to them. Jennifer McCabe drove Karen Read around to search; she did not bring doughnuts. Brian, Nicole, and Jen went downstairs to talk to the police officers. Brian knocked on Jr.'s door on his way downstairs.
John O'Keefe had already been transported to the hospital before McCabe woke up the Alberts. I'm not sure any fire personnel where still there, from what I recall from various first responders testifying. I don't think Karen Read and the other friend were still outside then either.
Much later in the morning, around 8:30 I think, Julie Albert (Brian's brother Chris's wife) stopped by the driveway to put half a dozen doughnuts in her nephew's car. Julie was not aware anything had happened. She wasn't planning to go in to the house, just drop off the card and present, and get to whatever she was going to do next.
Brian's actions were proper. The victim had been transported. A few police were on scene investigating, and 2 of the officers were there to talk to the residents when he got downstairs. As a professional first responder, Brian understood he had no role in the investigation going on outside. If he'd woken up earlier and could have rendered aid to the victim or assisted first responders trying to save his life, that would've been different. As one of the detectives said, saving a life is always the priority over preserving a crime scene.
The wild speculation about Brian and his relatives has been remarkable. The victim's mother and brother have been jeered and harangued when they attended hearings. Police and firefighters are being accused in court by the defense of planting evidence and tampering with evidence. And that's without Brian having gone outside to examine the spot where John had been lying. Can you imagine the furor there'd be now if he had inserted himself into the investigation by going outside? Yikes! Many believe seem to believe Michael Proctor was too close to the witnesses to investigate the death impartial, and Proctor was not involved directly in the victim's death nor had he been socializing with the victim in the hours before he died. Brian had been with the victim hours earlier. IMO, Brian acted professionally and responsibly that morning by not interfering in the collection of evidence and initial investigation. If he'd gone outside, he'd be accused on compromising the investigation directly.