This event requires the player to have an orbital beacon to send silver, and the lore heavily implies it's coming in over the comms console. But this event can trigger without comms consoles or orbital beacons even unlocked, such as in a tribal start.
Okay, since you sometimes have to pay them to get the location of the stash, it seems that disabling the incident if you don't have any comms console is the only solution. Fixed, thanks.