I cannot answer for Brother and please excuse my response, but I can fexplain why for at least some of us who are interested in this subject. After Vatican II, there was a virtual tidal wave of Liturgical abuses and attempts at virtual wholescale change within the Church. It seemed that everything new was considered good and anything traditional was bad This affected all levels and some of the worst offenses apparently took place at various seminaries. In fact the SSPX was founded not to preserve the Traditional Mass but to run a conservative Seminary for those who wanted no part of what was being taught or perhaps more precisely the way things were being taught at European Seminaries at the time. The use and preservation of the Traditional Mass was a sideline.
However, after a while, the SSPX ran afoul of the local Bishops for various reasons, depending on which side you believe. This set the stage for their loss of canonical status within the Church whichoccurred sometime later.
Now at the same time, more than a few people had become incensed over what was going on in some of the Masses that were being celebrated, and since the faithful were told repeatedly that the Traditional Mass had been suppressed,abrogated as it were, independent chapels began popping up which offered the Traditional Mass. Most of these chapels were staffed by the graduates of the SSPX,seminary so almost by default the SSPX became the face of the Traditional Mass movement although that was never their original intent.
So many of us are interested in their situation and status because **without them, the Traditional Mass more than likely would have disappeared,**except in the few areas where some older Priests were still allowed to celebrate it. In essence without them it is highly unlikely we would have any Traditional Masses at all being celebrated these days.