Michael never testified on anybody. More than likely, paid his way out and for whatever it was worth, his father's reputation. (Though he claims his own father wanted him clipped too.)
Exactly people wonder how he walked away like its a huge mystery, for a mil or two The Snake would've let anyone leave the family outside of his own blood
In the guide to the american mob Michael Franzese said that when the Snake in 1992 he put his hands on a copy of his book Quitting the Mob, began to tear the pages and scream.