Perhaps they all saw a brighter future with Carlo Gambino. What I'd like to know is did he have Commission approval? Albert Anastasia was a boss.
They probably did see a brighter future with Gambino--never go wrong following the money. I think Carlo by that time was aligned with Genovese, who was emerging as the top Don. As for the Commission: they probably rationalized the "unauthorized" whacking of Anastasia by remembering that he didn't get permission to take out the Mangano brothers.