The author is honestly going a bit overboard. It looks "forced", like he wants everyone to notice how his manga isn't for kids.
Also, the police in this series is kinda useless: these two siblings kill, rape, do everything and always get away with it.
Now, having proof and an article, why didn't the authorities come to arrest them?
The most annoying thing is that they didn't call the police but the yakuza, like wtf do you expect them to do? In a RL situation they would simply change plans, their actions in this chapter are simply the author delusions.