'I miscalculated', Wu Long thought as he followed the 9th prince.
The princes were far too young.
The 5th prince was only 19, and this 9th prince didn't ever reach 17. So in place where he expected a calculated action of an adult cultivator he met emotional one of a youngster with barely any experience, let alone an actual grasp on their situation or command of their subordinates.
If it was someone of the same age who grew up in a different set of circumstances, even someone still privileged to an extent like Young Master Kai for example, that wouldn't really be an issue, since they would possess a certain degree of maturity and self-realization.
And even that wasn't guaranteed in the world of cultivation, where the world was too harsh to let children experience it, and thus the vast majority of those born into at least decent circumstances were to an extent cuddled out of necessity.