OK, for people who want to crucify Youka right away, most likely Youka's network here is serving as a replacement for the historical Mohists. In Qin apocryphal histories, it is said that the Mohist school under its third generation leader secretly pledged support to Duke Xiao of Qin and started setting up a network of affiliated officials in all Warring States that strove to influence the states in ways that would benefit the reunification of China (Mo Di shared Confucius' belief that China used to be one state).
It isn't known if this effort survived to the time of Ying Zheng, but Mohists were the preeminent military engineers and strategists of all 7 kingdoms all the way to the end, and supposedly the secret deal between Qin and Qi was made possible by Mohists serving as messengers. Mohists were masters of mathematics and cryptography too.
When Qinshihuang suppressed the Confucianists and other schools opposed to the Legalists, he left out the Mohists. They eventually fizzled out of existence because their ethical teachings were absorbed into Confucianism and the Han peace made their military skills less useful to the state. This sounds very similar to what Youka is proposing here.