There were only a few dozen people left alive within the mining base, once Gus arrived. As he had soon learned upon arriving, many of them were children, left alive while their parents were killed by the uncaring aliens. Listening to Bryer, it seemed like they had only been able to survive thanks to their size, which allowed them to hide in small, unlikely places where the aliens couldn't possibly have thought to look.
They hadn't even had the chance to venture inside the mountain to where the mine would reside. Who knew how many souls they were leaving trapped in there?
It was extremely regrettable, but Gus could see no other option. A message would take too long compared to just going themselves, and once the message was given the Hringhorni might be needed to assist with the distribution of resources to affected areas, as well as the inevitable nightmare to fall on human territory.