Well it's easy to say now- oh he could rat on underlings like Massino or give up other heads of families....

But the whole point of RICO was to go after the top guys in theory. Hence at the time, Paul being head of the family wouldn't have thought about flipping since he would have considered himself the biggest target. Not saying impossible but u have to understand the era and mindframe these guys were in back then (old school)

Nowadays a boss would rat on his mum if he could and Feds would welcome open arms