In truth, Li Ling had already largely abandoned his impulsive demeanor from before after swearing the poisonous Heavenly Oath, so while his current action of killing in a no-kill zone was definitely one that came with great risk, he did it after careful and malevolent calculation.
One thing that males in the 'normal' world of earth understood deeply from a young age was the fact that rules only applied to select people, and even when the rules stated that those involved were to be punished, they could easily be bent to favor certain parties for various reasons.
A male understood this oftentimes as young as 5 years old on earth. The school one attended strictly stated that neither boys nor girls should enter the bathrooms of the opposite sex, but the reaction toward a girl entering the boys' bathroom and the reaction to a boy entering a girls' bathroom were vastly different.
