Apparently the Zottola's fucked over some people bad enough for them to already botch two hits and still come back for the third time. Even if it's drug gangs, blatant public violence is bad for business. Today's gangs know this as well as the mob. There had to be someone killed - like there was no other option.
And if they're not the ones behind the hit, the Bonanno's don't seem to do anything to prevent this either. Maybe they feel it ain't worth it or they just don't care.

Not to say this means the Bonanno's don't have anything to do with it. Vinny was close with some Dominicans, right? And people from his entourage had contacts with members from Hispanic and black gangs as well. I think I remember pizza telling something like this.
Who knows what happened...