Just from my experience as a woman, I cannot imagine these girls telling SUCH detail about a stalker to this store clerk.
Yes, the girls seemed vivacious and extroverted, from what we see, and I could MAYBE see them answering that they're in a group because one had a stalker.
However, this clerk went into great detail regarding said stalker, and it just feels off to me. At most I would think the girls would just say "we feel safer in a group" and leave it at that.
I agree about being friendly and chatty with clerks whom we see frequently, as
@seemstome said, so I figured that perhaps they went there daily.
Once he said they've been there a total of 6 or 7 times, I felt like nope, that's not frequent enough to spill every minute detail about where and when there was a stalker.
Also I totally agree with
@jcamh---they died mid-November, he claims he last saw them three weeks prior---he would've definitely said something about have a fun Halloween rather than leaping straight to Thanksgiving.
I agree with
@las726 that the vibe is weird. I don't think he's a bad dude or a suspect and it could just be the 15 minutes of fame, wanting to feel that he has something important to add to the conversation or whatever, but it just, in my opinion, seems like an implausible scenario. Not impossible but unlikely.
Jmo