If a split didn’t exist - there would be no need for “reconciliation”. If they were not on the “outside”, there would be no need to await their return.
I think you are taking a black and white view to something less clear. Yes, they committed a schismatic act, and even though the Holy See has repeatedly denied they are in formal schism it still remains a schismatic act. And many people point to excommunications to demonstrate this, though of course these have been lifted. However, many sins receive the punishment of excommunication and many public sins separate one from the life of the Church formally, however these people do not cease to be "Catholic." Many Catholics are good, and many more are bad, but they remain Catholic.
In the case of the SSPX it is clear that there was never any intent to set up a new Church. When the Lutherans etc. left they actively set up new institutional churches, which is nothing like the separation between Rome and the SSPX. That is of a different quality and nature. They are in error, and need to return, just as all those people in my Church with Obama stickers on their car. But, they all still remain Catholic.
Again - I just think we possibly are speaking a different language.
Maybe if I had used the phrase “fallen away catholic” or “catholic who is not in full communion with the Church” - then that may have cleared up some disagreement.