Castellano's well known love of money is why I reckon Paul took Nino's & RDM's side.
It should of been clear to Paul that DiMeo' and his crew was out of control by then.
Timeline i just read, the dead Cubans and the vacuum cleaner had just happened .

Wasn't the beef over the Epp's allegedly selling dope. What a bulls*it edict the 'dont sell drugs" was.
I'm sure it seems like " you deal, you die " only applied to some.

How were they related to the fat Mafia cop?