Why did it never cross Castellano's mind to whack Dellacroce? It would have surely curtailed a lot of problems down the line. Dellacroce showed no deference or respect to Castellano. No other boss would have tolerated it.
Gotti and Ruggiero were following Castellano's lead too. The reason they were so volatile and confident in taking out Castellano is because they were following Dellacroce's lead.
And so what if Castellano was banging his maid. Gotti and Dellacroce had bigger skeletons in their domestic closets!
Dellacroce showed nothing but respect for Castellano. Dellacroce was following Carlo Gambino's wishes and remained loyal even though he was next in line to be boss. It's no coincidence that Gotti killed Castellano shortly after Dellacroce's death. Dellacroce never would of allowed it to happen while he was alive.
