It has always struck me too, as somebody who had this very well planned, then it seemed possible somebody who is getting cover from anyone else who may know of something having gone wrong. The crew, however salty, LE hasn't shown any suspicion toward BM and his crew. Maybe LE should at this point, especially that security guard that was so into her phone during the June concert. I still don't understand why she would not keep her phone with her when she had so much else in her hands. Was there somebody she may have been avoiding, as such. If so, who could that person be?
The idea that the POI is somebody who knew what they were doing and Chelsea had the bad luck to run into them and feel safe enough to walk away with them is the most compelling. When and where she went missing, at what would be last call time, in a public venue with little security and masks, makes me think she was a victim of opportunity and not so much targeted from before. I think the POI wanted to leave with somebody that night and took his chances with Chelsea.
It may be possible the POI may be familiar to BM's crew and associates on some level but that it's tough knowledge, the kind you can pretend not to know or put two and two together deliberately, to avoid. I suspect, but mostly hope somebody knows something and can be moved to share it.