Vigano was Pope Benedict’s right hand man during Benedict’s papacy. He and Vigano were starting to uncover some major Vatican scandals (e.g. Vatican Bank, sex scandals). Benedict likely foresaw how he was going to be attacked if he further investigated those scandals. Perhaps he just didn’t have the stomach for fighting, and/or maybe he had some skeletons of his own that they threatened him with if he went forward. After he stepped down, Francis put the kibosh on those investigations.