1.Some things are seen or unseen.Some would point out that all things are either seen or not seen.
2.The baptism of desire is not seen. It is invisible.
3.Lumen Gentium 16 is being interpreted as being visible or invisible, seen or not seen.
4.The FSSP choose to interpret LG 16 as being visible.Someone in invincible ignorance saved without the baptism of water in 2016 is seen.
5.They can now choose to interpret LG 16 as being invisible.So also with LG 8, UR 3, NA 2 etc.These are references to persons not seen.
6.So this is Feeneyism. They choose Feeneyism instead of Cushingism as a theology. They choose to see through Feeneyite lens.
7.Since this is rational, traditional,non innovative and non heretical they would expect all Catholics, including the popes and the Congregation for the Doctrine of the Faith, to do the same.
Agreement in public on these points would help the SSPX reconciliation and the Vatican's return to the Faith.Since the doctrinal scenario would have changed.With Feeneyism, Vatican Council II would no more be an issue.The Council is traditional on EENS( Feeneyite).
EENS( Feeneyite) was the basis over the centuries for an ecumenism of return, non Christians needing to formally convert and the need for the Social Reign of Christ the King over all political legislation,with the non separation of Church and State.
Parishioners at FSSP parishes could in public, also affirm these points.