For decades McGuinness swore he was not at the "bloody Sunday" march until he was basically forced to admit it.
The IRA like a lot of the Protestant groups were up to their eye balls in organised crime as well. They're not chivalrous freedom fighers mostly despite the continued support of Fenianism from America.
Catholic does not necessarily mean republican. I think that about 65% of Ulstermen are Unionists at the moment. I personally think those border counties that are very much Republican should be given to Eire.
Maybe in Antrim and Down, but most definitely not in Armagh, Fermanagh, Derry, or Tyrone, which all currently have a Catholic majority.
There may be an overall Protestant majority, but in 4 out of 6 counties there is a Catholic Majority. Not really a convincing argument regarding "vast majority" of Northern Ireland being Unionist.