It comes down to England's imperial ambitious in Ireland, a place with a different people, culture and religion. Northern Ireland is just an English colony, plain and simple. Scotland experienced a similar fate with english genocide in the 17th century.
Historical, england acted in the wrong. Granted, it is the story of human history everywhere in the world. Power.
But don't play the moral card now. It's just a matter of continuing the peace process. I'm not sure this event helps it.