"Those people probably have a harder time surviving since the appearance of the zombies, so there's probably not a lot of them left."
Most of those talented people probably had a harder time surviving, as they had to run and fight zombies if they wanted to.
Of course, if their talent and environment allowed them to invent something that would help them survive, then they're certainly still alive.
However, such talented people wouldn't be too easy to find, so it's understandable that they hadn't met any that they could take.
As for the small bases that they had passed by before, there were probably a few, but they were also utilizing them, so they wouldn't be able to take them back to the North Base.
Of course, if they had been exceptionally talented, Yang and the others would certainly try to persuade those people so that they could go to the North Base, and they certainly wouldn't forget to report it to Treyton.
