With this new info about leaving a friend's place at around midnight on the 13th (spending hours there after having been at the tavern) makes it even less likely it was BL, imo.
We know the two witnesses for the GP & BL Moab police stop report were both male and not likely to be employees of Moonflower judging by their released statements/calls.
It is presumed that BL and GP reunited on the 13th (the separation having occurred on the 12th) and even if they didn't leave Moab that day and continue on towards SLC, GP would have been with him.
How does the timeline fit with K&C leaving a friend's place alive and well 12am - 1am and going to their remote campsite? Does it seem that likely that BL would have stalked them from the tavern and waited for them outside that long?That would also mean that he had to have had the van back to travel to the crime scene, which means he would have definitely been with GP. Can you honestly see her staying with him for two more weeks afterwards, if she had witnessed him following, stalking, attacking, raping and murdering/shooting these two women in cold blood?
Also the type of crime and use of a gun as the murder weapon seems very different from what happened to GP, which appears to me to be a very textbook personal DV murder (manual strangulation of an intimate partner).
It just doesn't make logical sense for BL to be a suspect in this case, in my opinion. But the private investigator is being very savvy to keep using BL's name in the media to raise public awareness for the case.