I don't know if I can see a single guy whom can be charismatic and strength possessing to maintain being the only guy on top and run everything in Montreal. Outside of Vito Rizzuto (Who even had his father and surrounding family), we haven't seen it work. I don't know if I necessarily believe Nicaso's theory, but it's plausible. However I do believe that at the end of the day, it'll be almost like a confederacy, a group of guys whom control the Montreal Mafia.
John Dubros book Mob Rule covers Cecil Kirby a little bit. And he told pretty much every single thing he was asked to do by Cosimo, and Remo too. I can see why the bikers wouldn't be trusted I guess by those who came immediately after them, but there time was long ago, I'd be surprised if that still held relevancy, like you said.