The more I think about the meeting in that gazebo, the sillier it becomes.
So, Greyworm was slashing soldiers throats in the streets because it was a direct order from the queen that he serves to kill the enemies. Jon stab the very queen that gave him that order, the ultimate betrayal. So Greyworm is like "I'm gonna jail you for MONTHS while the head of the families come over here and figure this out!!!!" (Mind you, at that meeting, Greyworm said that Jon Snow is his prisoner implying nobody could object to what he decided, so why imprison him for a long time to begin with?).