Well, there's really no percentage in a mass murder like that. Like Michael Corleone told Tom Hagen, their soldiers are businessmen. They'll go where the money is. Considering all of the dons that have been overthrown, murdered, etc. by other wiseguys, it seems to make little difference to the soldiers who leads them as long as he's fair and helps them make money.

The NJ family is small. They seem to have more captains then they need. It wouldn't be a fair fight and Tony knows it.