It's more about the Gambino Family heading off the Genovese Family in respect to the Javits center than anything. Without going on record with a mob family the Westies would all be whacked by the Genovese and Javits would be their own personal fiefdom. Coonan was smart enough to know he needed to be put on record with a family to avoid open season on his gang. Best way to do that was to conspire with DeMeo to do something big that would cause a huge sitdown requiring Bosses, ub, consig. Etc. Which whacking Ruby did. Gambinos grab 10 percent and a foothold in Javits, DeMeo gets his button, and Coonan on record with the Gambinos gets his protection from the Genovese. Very well played.