We all know he's a fat rat piece of shit but the question is, why did he lie about Pistone? Massino was looking to obviously get a free get out of jail card and a great deal for himself and family. So, why would he invent that about the FBI's most revered agent? He would have said Pistone walks on water and parts the Hudson River instead he said that Pistone was suspected and that Sonny Black was not killed because Sonny took him around. but because he was making a move. Why piss off the Feds and prosecutors? It doesn't make sense. The feds would have canceled any deal that they had with him instead of rewarding him.
Also, keep in mind Ralph Natale was heralded by the FBI as the first boss to ever flip, but we all know the truth about that story.