All that is predicated by knowing coalsack is where this was going down. Without that info, nobody would have even thought to have gone that way; indeed the investigator trail in local Galnet may well have pushed more interest towards Barnard's loop on a false hunch before thinking to check the coalsack, could've been days before that happened, since Pleiades, cone sector and whn have been focal for goids to date.
Actually it seems to me that the Sidewinder data core
does lead pretty directly to the Musca Dark system. Says Prof Carver in the log:
This sounds crazy but even though the nebula is three hundred light years behind us, it feels like it's reaching out, trying to drag us back...
Not only is Coalsack the only large nebula nearby in that general direction, but the Musca Dark PJ-P system where you started the day is 295 ly from the crashed Sidewinder. Even if many of the searchers were misdirected towards Barnard's Loop, this clue is clear enough that I think some number of folks would have gone to check out Coalsack, even without the binary hints. And as you say, once folks are looking there, it would be rapidly apparent that there are barnacles where there weren't any known before. And since it's well known today that barnacles mean Thargoids, that would lead people directly to searching M-class stars with Ammonia worlds. By my count, there are only four systems satisfying both conditions - has an AW and a single M-class star - within 50 ly of the center of the Coalsack.