Originally Posted by Evita
No doubt something as big as this would have needed the backing of someone like Barzini not "Tattaglia a pimp-- Should have raised red flags It is the Consigliere's job to suss out

I reckon Vito's participation was essential otherwise why would Barzini still need Don Corleone's judges and politicians even after that long
My take, for what it is worth!

I watched the peace meeting scene closely! as to why Vito's participation in the proposed drug operation was so vital, critical to it's success and it seems -
Extracts:
  • Tattaglia stated “Vito had ALL the judges and politicians in his pocket. He refused to share them”
  • Barzini stated “Don Corleone had ALL the judges and the politicians in New York, then he must share them or let us others use them”
  • Even though Tattaglia and Barzini seem to use 'had' the discussion was in the present tense ie: they were still after Vito's protection even after that long
  • Barzini concluded “Don Corleone will give us protection in the East and there will be peace”
  • Does this mean the other New York families did not have political and legal influence? Hence Vito's protection was essential for the proposed drug operation
  • The drug operation in New York was not up and running? even after that long
  • What I found even more telling is Tattaglia's “as time goes by and Vito's position becomes stronger will he attempt any individual vendetta?”
  • So, even though Vito was in a 'weak' position, the other families couldn't prise the judges and the politicians away from the Corleones
  • The judges and the politicians were still in Vito's pocket and remained loyal to Vito as long as Vito was alive

Thus I also deduce that Vito's participation and protection in the proposed drug operation was essential indeed