He was present in 1082 when the church of Notre-Dame de Mortain was given to the abbey of Marmoutier and subsequently turned into a priory.
[1][2] Up to 1088, he was quite involved in the duchy's affairs, helping in the reconciliation between the archbishop of Rouen and the abbey of St.Ouen in 1073, and witnessing the foundation of a priory outside his diocese (Saint-Marie du Rocher, in 1082).
Michael apparently accepted the agreement, unlike his warlike colleague the bishop of Coutances, Geoffrey de Montbray.
This event seems to mark the end of Michael's involvement in ducal affairs, and a cooling off of his relationship to both Robert and Henry.
Moreover, his last recorded public appearance in 1093 was at the funeral of Geoffrey de Montbray, a well known enemy of Henry.