Although the media simplifies this whole dispute between two large factions, I personally believe tensions originate in a generational conflict within Montreals mafia with what I call the Sub-40 group.
This sub 40 group was opposing the established cupola, Renda, Rizzuto, Cun-trera, Arcardi etc.. , and wanted to establish itself and not have to pay tribute to the remnants of the Rizzuto clan after Colisee.
Think that Scoppa was in his early 40s when Colisee occurred, add to that Montagna, Arcuri, Lopresti, Colapelle and so many others who were subject to the Rizzuto clans tax and control within the Italian milieu.
These men, De Vito for example, were not willing to kick up and submit to men such a Nick JR and the second generation of Rizzuto clan members it seems. The bars and cafes that did not suffer any or if little molotovs between 07-12 were all part of the initial coallition and the sub 40 group.
Obviously Montagna accelerated tensions with other established players in Montreal.
Also I noticed another pattern, many members killed in the Rizzuto clan were above a certain age and part of a certain prestige.
Antimafia, as for Montagna and his role of effect, its undeniable that he may have propelled the coalition to overthrow the old regime. That being said, I had heard rumors that many in Montreal used him and his ego to fuel his ambitions.