“This is all I can tell you, I do not think Rome will let us go. The Modernist Rome [sic] will come close to us [once again], it is inevitable. They are determined, they are persistent, they want to lead us to the Council, therefore pray. Personally, I would never sign things like that, that is clear.” 
Bp. Bernard Tissier de Mallerais, SSPX.
And there is nub of the dilemma; is this Society to follow the path of the Lutheran Self-will and modernist, opinionated sub-magisterium as a guide to the reunification of Rome with the Society, or will it – as a group for the service of the whole church catholic – truly offer a submissive obedience to the divinely appointed (though disliked) Magisterium and its authoritative (if at time ambiguous) Teaching .. for that authority keeps watch over them also (with much sighing)?

“Obey your leaders and submit to them, for they are keeping watch over your souls and will give an account. Let them do this with joy and not with sighing — for that would be harmful to you.” Heb 13 : 17.

This is a matter of Rome accepting the Society by rejecting the divinely allotted teaching authority it is called upon to express in the body of Christ; the good of souls is clearly made secondary to the political independence of the group in Bishop Tissier de Mallerais’ short but telling sentiment (on obdurate personal will); so, it seems, Rome must abandon Peter and Paul or not be reconciled to the will of the Society of Saint Pius X, rather than the SSPX – with simple charity – loyally witnessing the egregious confusions clouding the hermeneutic of continuity in the conciliar documents, the appalling implementation of these at times confusing texts as authorised by the Magisterium, and the subsequent confused abandonment of a Sacred Tradition as the divinely gifted treasure to be used as the Church’s standard measure of sound teaching, 2 Tim 1 : 13-14.