So there comes a helicopter shooting all the dons in Atlantic City. It's like in the Army where you shoot them a mile away. Let's assume, Altobello knows how to hire a helicopter and Vietnam veteran assassins who know how to execute such an attack.
Can we believe that the New Jersey police department (or FBI, whoever is in charge) is so incompetent that they wouldnt find out who had steered a helicopter that night?
I've never been to New Jersey but I can't imagine that after the attack the helicopter could dive into the usual helicopter traffic jam at the New Jersey sky.

Inspector: What did you find out about that helicopter attack?
Sgt.: Not so much. There were just too many of them.
Inspector: What about the helicopter of that old Altobello?
Sgt.: Well, if it was him, he used a false license plate.
Inspector: Alright, let's close the file.