The Apostles gathered Around Peter Is the Primary Symbol of Catholic Unity

This piece from an Australian Jesuit run site makes the clear case for proper context when considering both the recent lifting of SPPX excommunications and their imposition in the first place.

Of course Australians have an interesting ecclesial context of their own, in addition to the universal one, for looking at the question.

Pope Benedict's decision to lift the excommunication of four dissident Bishops has caused controversy. It has largely focused on the anti-Semitic statements made by of one of the four Bishops, Richard Williamson (pictured). Church authorities on all sides have since scrambled to disown Williamson's attitudes.

But the Pope's decision also raises wider questions about the unity of the Catholic Church. These bear on a current conflict within the Catholic Church in Brisbane...

The disciplines that Archbishop Lefebvre ignored and the excommunication of the bishops were designed to safeguard the unity of the church in its faith and life. The decision of the Pope to lift the excommunication reflects a desire to restore unity. From his perspective it is a generous initiative, a circuit breaker, to heal division.

The gesture does not re-establish the unity in faith and in life between the Catholic Church and the followers of Archbishop Lefebvre. That was damaged before the 1988 ordinations. But it opens the way for conversation about what restoration of unity might involve. ...

The opposing claims of unity, identity and local autonomy in churches, as in societies, always need to be negotiated. The negotiation is always delicate, because in any dispute what each side prizes is precious. Pope Benedict's generous gesture, together with the projected acceptance of dissident Anglican congregations, has put into play the understanding of what unity entails.

(emphasis supplied)

It is very hard, as a Robertson Davies character might need to learn, that one is only "fifth business," but those wailing and gnashing their teeth over someone so evil and mis-guided as to impugn Julie Andrews being a part of the family may need such a lesson.