The problem with your moral contortionism is that it is irrelevant in the context of the political ambitions of your Party as what happened 100 years ago is not an obstacle to Irish Unity. What happened 20-50 years ago is.First, there is sometimes a tendency to relate to events of the revolutionary period of 100yrs ago as a having some sort different set of values and morals.
In any negotiations about a united Ireland FF or FG having a heritage of insurrection and conflict doesn't matter. SF having a leadership which engaged in conflict and terrorism does.
Seamus Mallon said we should hasten slowly towards a united Ireland so that we don't do to the Unionists what the Unionists did to the Nationalists.