How to understand "if Hanoi is fierce, it will move its people to Hedong and its millet to Hanoi"

From my own country, it is about Liang's way of governing the country. "If Hanoi is fierce, it will move its people to Hedong, and its millet will be in Hanoi." The word "people" in this sentence should be understood as "young people". Zhu explained it this way: "Immigrants can eat whatever they want, and move millet to those who can't move it." Zhu's explanation focuses on the left-behind young and old, noting that young and old can't walk around. If it is really for disaster relief, there is no need to emigrate, which involves many factors of social stability such as family ethics. This is why Mencius said that Liang's policy was "pot calling the kettle black" and did not play a fundamental role.