It doesn't seem like Rizzuto ordering the hit on Montagna adds up. If it were Rizzuto's men that killed Montagna, then it would make sense. However, it was Desjardins and his guys that killed Montagna. It's pretty clear that Desjardins was on the opposing side of the Rizzuto clan and it was in retaliation for an attempted hit on Desjardins.... Don't get me wrong, I don't think Rizzuto was upset to see Montagna get whacked, but in my opinion it wasn't on his orders.