You confuse being put out of the Church and being stripped of the authority to perform sacraments with the capacity to perform sacraments.
When angelo became a "born again" Jew, he did not cease to be a baptised person. He was baptised and that is irrevocable. Why? Cause God changed the person. He doesn't take back what He has given.
A priest is changed by God to be a channel for Christ in the sacraments. Nothing can change this "change." It is.
When someone ceases to be a Jew, his foreskin does not grow back. In the same way, when someone abuses his power as a priest, he may face sanction or dismissal from the Church, but he can not "unbecome" a priest any more than he can become "unbaptised"
Since he "understands" completely, please direct any further questions to in_principio_erat_Verbum. Thank you.
SD