I understand what you’re saying, but I think that I have to agree that the SSPX, if brought home, could provide a wonderful service to the Church as a whole. I think that what we could use today are people who are not afraid to demand reverence and respect at the Sacrifice of the Mass. My hope would be that, if the SSPX returned home, they could help educate people on how to celebrate the Mass faithfully. This isn’t to say that there aren’t people in the Church now that do that, but the more voices in the Church that call out for more respect in the Liturgy, the better.
It seems to me that this is all tied up with the whole concept of “reform of the reform,” in the sense that the Holy Father is calling for a true application of the Second Vatican Council, and for people to follow more closely the rubrics of the Liturgy. In this way, I think that there is a definite role for the SSPX to play, but the first step is for them to reunite with and submit to Rome.