Hear me out before I go full conspiracy theorist here but this seems that whoever did that wants us to know that the people vanished, and wants us to follow up. The tracks north of town are kind of obvious as well, pointing land inwards. Plus, why would a 'pest control kit' contain blackfinger's salt? And why would it be written down in an inventory? There is either someone betraying the settlers, or someone trying to frame someone else as the betrayer. Maybe both.