Yeah, I remember reading that exchange too:
I think a lot of it was timing, Dellacroce was in jail for the tax thing when the BOss question opened up.
I think he didn't move because they showed him a lot of respect just waiting for him to come home before naming a boss. From what I understand if they tried it the other way, he woulda had to respond just to save face, by waiting for him to come home, and not doing a Costello and demoting him, his respect was kept intact, as well as his financial stake.
Also, I think DEllacroce was just saaavy enough to know he was the power in the family anyway.
It reminds me a little of what LEonetti said about Scarfo in his book, that even though Testa was boss, the most powerful guy was SCarfo, that when it came time to exercise power (murder) Scarfo called the shots, same with the Gambinos and Dellacroce, 3 capo hits, Galante....
His guys loved him, a lot of people don't understand it's very hard to win a war vs a guy with a loyal crew, it's why MAranzano beat MAsseria, shit it's why gotti got away with killing Paul, no one loved Paul enough to die for him, plus losing Paul didn't hurt enough guys financially to provoke a response.