I personally don't blame him for turning his back on his boss Joseph Magliocco, and reporting the murder plot to Tommy Lucchese and Carlo Gambino because they were two of the most powerful of the five families at the time, and The Gambinos could take on three of the families at the same time alone. It would be career sucide if he tired that.
Gambino wasn't some sort of god
there's no way he could have took on 3 families on his own, his power came from his allies at the head of the other familes. I assume you were including the Genovese in this and i'm not even sure if the Gambinos were bigger/more powerful than them at the time.
