That Dad said they were sleeping in the same bed doesn't compromise the investigation at all, because it is doubtful that law enforcement told him that. He is probably making a reasonable assumption (a likely true one based on his experiences), and is rationalizing his grief, which any of us would do. We would all hope that our children didn't die alone, and if there was any chance that they didn't we would err on the side of optimism.
My opinion.
This troubles me.
If true, this fact, so far, been known only to the killer and the LE team.
This detail could explain to some detail what was on killer's mind when he went to kill and did not stop until he killed 4 people. It is purely insider's information and the parent should have thought of why LE is not willing to disclose it. Because LE have reasons not to disclose this and others known only to them and the killer facts. Such as where the dog was, where the bodies were, which flatmate was attacked first etc. Just to name few.
Why do you think they do not want to disclose? Hardly unlikely just because they want to keep their cards close to the chest.
There are other reasons.
Imagine that tomorrow someone goes to Idaho police station and says 'i did it' and starts telling a story based on facts which mostly media and some of the parents are so willing to report.
Then, the police starts investigating his story, allocating resources and effectivelly stops investigating other leads they have now.
Only for police to find out 3 weeks along the road that this person has nothing to do with the murders. He made it up, but because there were so many details of intimate pictures of the crime scenes, this person easily fooled the police, albeit for a while, that he is the perpetrator.
In meantime, the real perpetrator goes away with murder.
Do you think this is not a compromising of an investigation?
And who will cry first that police are incompetetnt?