I am not a student of this disagreement but it seems that the Vatican has offered an apostolic adminisitration, no?
Doesn't that mean SSPX could go and set up anywhere? It's not all what they want, but it's a good start. Let their works shine forth, and the rest will come in the Lord's time. Archbishop L signed VII documents and celebrated if briefly and rarely the NO. He signed the 1988 agreement.
Why not accept it, be officially inside, and not be subjected to the smears of heretics?
I don't disagree with your thinking generally, but would note that the Society of St John Vianney, in Campos, Brazil, which did accept the apostolic administration proffered by Rome (by Cardinal Castrillon Hoyos, of the Ecclesia Dei Commission), has found that it cannot in fact operate anywhere in Brazil except in the Diocese of Campos. I understand that this was NOT the original understanding of the deal by the SSJV, that in fact they thought they would have the right to operate (and say the TLM) anywhere in Brazil, but this was quite rapidly denied them AFTER their reconciliation with Rome. Thus more fuel for the fire for those in the SSPX who didn't (and probably still don't) trust those in authority in Rome.
Perhaps there will be more favorable developments under our current Holy Father, however. We can hope and pray (a lot) for that, as the reconciliation of the SSPX would be a great help in the (correct) renewal of the Church that I am sure our Pope wants very much.
Then you have to go along with the Vatican II newspeak. It is not Catholic the New Ecumenism, the New Evangalization and the "Novus Ordo" novelties of a Mass.