no doubt there was collusion, but looking at it from start to finish from 1969 riots, RUC in Derry, burning out of catholics, Operation Motorman/Rape of the Falls, Internment, Bloody Sunday its fair to say that there were some compelling reasons as to why the IRA emerged and had support - it hardly having existed around 1969.
However from around the mid 70's it was fairly clear that there was going to be no military victories on either side, and the IRA 'long war' was pointless and blood thirsty. So you got Kingsmill massacre (pick out the 1 catholic & shoot the 12 protestants), Le Mons (firebombing ordinary punters), Bloody Friday (spate of bombings across Belfast in civilian areas), Pub bombings in UK (maybe a suggestion these werent "official jobs"), Mountbatten, Hyde Park (famous for the horses....), Enniskillen and I'm sure another 10 or 12 that had no 'military' justification (and thats presuming you accept all military targets were justifiable in a "war"). Then there was The Dissappeared, torture, community control and punishment beatings, one could go on. So basically there was total disregard for civilian life and collusion came in the 80's - not that it was justifiable but its clear no-one was adopting Queensbury Rules, so to speak.....
Why any of this is relevant is that McGuinness & other senior leaders have a lot to answer for, ok he was eventually cajoled into the peace process, but a couple of decades (at least) of pointless killing and then lying about your role in it are hardly the credentials you'd be looking for in your ideal candidate.