Supposedly Sindone and Scarfo hated each other. Frank was called "Baracuda" for a reason. He also had a previous drug conviction and Scarfo notoriously hated drugs and drug dealers. Sindone may have wanted out of the life and to enjoy his money, but he was also complicit 3 years later in the plot to kill Bruno. Being Bruno's #1 loan shark with gambling connections throughout Philly and down to Baltimore and being closely aligned with Tony Bananas, Sindone was expecting to become Caponigro's underboss. Obviously, Bananas was whacked and this never came to pass. Before Testa was made boss, I believe Sindone won the internal vote (from the capos/soldiers) to be boss but didn't get it as Phil was made boss by The Commission (think this was mentioned in The Plumber).
It's funny how this all comes full circle...Testa feared Sindone's power and loyalty, so he used Sindone's right-hand man Chickie Ciancaglini to set up Sindone who was killed by Chucky Merlino. Fast forward 13 years, and Stanfa (who like Sindone was in on the plot to kill Bruno) is at war with Chucky's son Joey and Chickie's son Michael...and the beat goes on...