I'm not sure why McCarthy chose to approach this as a theory of victimization, saying the solution is to harden society. I guess in technically he's correct, they are choosing victims based on their vulnerability, but at the same time, there are elements of criminal organization.
These kids are basically roaming as a "gang", so it's definitely a problem for law enforcement to solve, not citizens. Yes, citizens could arm themselves... but citizens will not solve any sort of organized crime on their own without taking extreme measures. Police, politicians, and the courts should definitely be accountable for this one.