the excuse to go against Bonanno was because Stefano was forcing the issue about his territory in Canada.

Bonanno was meddling in the affairs in the California mob, trying to stage a coup on Frank Desimone.( the Jack Dragna organization had ties to Luchesse)

and Bonanno claiming territory in Arizona, brought problems with the Chicago outfit.

so in theory, this along with wanting to control the drugs and garment/unions in New york is enough motivation to try to destabilize a Boss's power.