When the state breaks the laws it upholds, it leads to a degeneration and deepening depravity of the system it represents. How can you ask someone to behave peacfully and lawfully when you break the law yourself so openly.
And this (the Paras murdering their own citizens at a civil rights march) is just one event. There was widespread collusion between Special branch, RUC and military intelligence and terrorists, leading to many innocent people being murdered. There was widespread infiltration of terrorists by the security forces, to the extent that innocent people were murdered to protect intelligence assets.
It was a very dirty war. On every side there was law breaking, murder and corruption (the racketeering, with tacit police approval in certain communities caused much hardship and damage).
The side for governance, law and order were just as murderous, duplicitous and corrupt as the people they were fighting/resisting. How can anyone be surprised when things got a lot more bloody and violent when the state was giving everyone a big push from behind?