These acts of vandalism were far from random, and I think you meant "excusing" rather than "rationalizing".
I'm not sure I understand. Regardless of whatever pebble started the landslide it's my understanding you had a lot of pure thug acts of violence and vandalism. As for excuse vs rationalize they are often functionally synonyms.
broadly : to create an excuse or more attractive explanation for <rationalize the problem>
A window of opportunity presented itself when the police force surrendered its legitimacy for that period of time. Teenagers, blasted from birth by bourgeois messages, without access to Eton, with parents working graveyard shifts, and with adult "role models" like David Cameron whose wealth was generated by his great grandfather's war profits looting China and the distribution of opium....
Then what you have is a vignette which brilliantly captures the irrationality of bourgeois society.
As for the rest of it there are few things I think less of than a mindset that says "my life could/should be better so I feel justified in pi**ing on other people's". There are people dead dude, including a 68yr man that was beat to death.