It might clarify things by reading the writings of the actual St. Pius X, especially on the importance of Catholic Action. This pope not only wrote about Tradition, but also about the current need for unified Catholic action. This involved the laity working under their pastor and bishop-ordinary, not just following any priest or bishop who happens to be ordained.
He also referred to laity working alongside other laity and **pastors **to promote social justice, and oppose then-current evils that are even stronger now, on a diocesan level, national level, and international level. None of this would happen without obedience to the living magisterium.
Today obedience to the living magisterium is lacking, mostly on the Left but also on the Right. We live in an anti-religious-authority era. If you go to a religious retreat house where the anti-religious-authority temptation is especially tempting, you might learn something about St. Ignatius Loyola, but also you absorb other things. We all tend to think, “I’ll just take what is good and leave the rest behind”. But your attendance there encourages other attendees, and the people who run it, to continue listening to that anti-religious-authority temptation, rather than people like the real St. Pius X, and his call to Catholic Action.
Suppose the SSPX priest happens to be wavering, undecided about whether to unite in ministry with his bishop ordinary and the pope. Your attendance here may help him postpone what may be a positive decision for him; and postpone that needed FSSP retreat house in Western Canada.
