IMO it'd be far more notable if they were NOT saying they were combing their SM and that it were important to the case.
To me the SM accounts for the girls HAS to be the key starting point aside from whatever they've found at key - as it is in many cases nowadays anyway.
But in this in particular we know we have cell pings showing their location bopping around the trails, etc.
Plus the info gained from things like the texts Grand Patty said he knew were delivered but never read helping with possible timeline.
We have more visual SM accounts - SC, FB, IG, etc. - that are all providing video and photo access of their day/wanderings, at least some of which was within what was probably within at least under 120 minutes of when they were killed.
In a remote area where not many people were around, the background info from those images, who viewed them (you can see that with some of the programs) and when, who may have liked or commented and when, etc. plus clues as to their route/timing/etc. via SM, are all especially apt to be helpful in piecing things together in this case and possibly finding info about who was involved and timing and specific locations of things purely based on clues from all the visuals the girls themselves provided.
So like I said, I'd have been MORE surprised if they said they did NOT think the SM accounts of the girls were useful.
Plus of course there's the fact that investigators always look at that these days to check out things like possible arranged meetings, who people have been associating with or in contact with, etc.
But all of that latter bit, IMO, is rather par for the course now and the rule not the exception.
I just think in this case, aside from forensics at the scene and any possible actual witnesses who saw or heard anything, the SM accounts for the girls would HAVE to be a key component of this purely because more than in many cases, we know there's documentation from leading up to their murders far beyond "just" cell pings like we might have in most cases simply because the girls were using their SM accounts actively to document their outing.
