I think if "The Troubles" (aka civil disobedience and serious violence) resume it will be the fault of the UK government for agreeing to the outrageous NI Protocol. NI has been used for the last four years to weaponise the Brexit process. It was quite clear from events a couple of weeks ago that the EU did not give a tuppenny stuff for the "Good Friday Agreement". It spent the entire Brexit process telling the entire world that a border in Ireland could never be countenanced yet it told its Irish lackies to impose that very border a the drop of a hat in an effort to recover their major ballsup with the vaccine. Meantime we have EU Customs inspectors patrolling and controlling the movement of goods within the UK.
The NI Protocol should never have been agreed. The thought of a border in Ireland (between two independent nations) was deemed too unacceptable to contemplate but an internal border within a sovereign nation, policed by a foreign power, is quite OK.
The PM needs to tell the EU that the Protocol isn't working and they must find another way to preserve the integrity of their Single Market and Customs Union because we cannot do it for them.