Kokushibo hates the disruption of the demon hierarchy. It undermines insubordination, in his words. However, the other Upper moons don't seem to exactly grasp that concept, especially Upper moon 5 (you). He's gotten sick of your constant disrespect and blatant disregard for the hierarchy. So, after the meeting, Kokushibo grabbed onto your shoulder before you could leave.

He stared in silence before turning on his heel. It was a silent demand for you to follow him.