Some people, like General Gui, would rather die rather than serving Fei Yang Kingdom. While his loyalty was admirable, there were not many people who would be able to be the same as him and said that with certainty.
The moment they chose to refuse following Fei Yang Kingdom meant that they would be sentenced to death along with their family members.
Thus, some other commanders chose to bury their resentment.
And it was also because of this that Emperor Yang Zhou didn't dare to recklessly reuse these people if it was not necessary. General Kai at the north border was just one of the few cases that they chose to use because of some reasons.
Besides, they have already deployed some commanders to the north during this period of time and Emperor Yang Zhou felt that it was unnecessary to worry so much. Even if General Kai wanted to rebel, it wouldn't be that easy.
He was surrounded by four kingdoms.
