Lots of people are puzzled by the extraordinarily generous treatment that Bergoglio has afforded to SSPX. After all, wouldn't SSPX be the epitome of the "rigid" and "Pharisaical" "doctors of the Law" that he so regularly excoriates? And yet no terms of "regularization" appear too generous--it seems that anything SSPX asks for they'll receive. However, if you keep before your mind the idea that Bergoglio has a specific goal always in view, matters become a bit more clear.
What is Bergoglio's goal? To fully implement Vatican II--as he understands it. And he has made no bones about the fact that his version of a true Vatican II Church would be in line with the views of the most radical of the New Theologians, such as Walter Kasper. How could empowering an organization such as SSPX, which steadfastly rejects precisely those elements of Vatican II that are so central to Bergoglio's plans--ecumenism, religious "freedom"--possibly help Bergoglio fully implement his goals?
To come to an understanding of Bergoglio's strategy, the key provision of the proposed SSPX personal prelature is the one that allows SSPX to incorporate religious congregations.