I think that Winegardner has an axe to grind with Michael. He's very quick to point out what he perceives as Michael's shortcomings as a Don, while singing Geraci's praises. He knows that he couldn't eliminate the Corleones completely so he gave them a backseat to the Geraci character.
"I got news for you. If it wasn't for the toilet, there would be no books." --- George Costanza.