I am wondering if they DID have sex, or just said they did, as alibis. Maybe even faked some photos of such. They had to show some reason for being out and about at that hour, in case they were pinged or caught on tape, which apparently they were.
I wish we knew more about SM. I still feel like we know next to nothing. There was a reason Heather was involved with him for six months or so; it wouldn't take that long to find out he was a total loser, for instance, IMO. So he must have had some attractive qualities for her to want to be with him for that amount of time, which is fairly significant at age twenty, IMO. Away from TM, he may have been a totally different person, but we don't know if he was his true self with Heather, or with TM. No one has had much to say about him.
All jmo...