ONLY when he went away did that happen. They wouldn't have dared to pull that move if he wasn't in an American prison at the time. Vito showed his power when he got out and Di Maulo was dead in about a month and it continued from there.

As for Arcadi I would say he is in the best position to try a takeover, but I haven't seen anything yet that shows him "out of favor" with the Rizzuto faction. With him being in a halfway house for 3 years and under restriction that long, I'm not sure he can afford to pull a move. He can't even meet with Del Balso and Giordano for another 3 years, but I admit I don't know the Canadian laws that well.