Crickets in this thread. Xavier's position is basically that the Pope and the Conciliar Church, and the Vatican 2 Council, are completely legitimate and are the real Catholic Church - but that he can also choose to ignore its Magisterium and the orders of its rightful hierarchy, including going to Masses of Priests barred from holding Mass(a pretty serious offense), in a state of effective schism. I don't understand how he can't see the problem there.
It's different from +ABL and the standard R&R opinion in that, unlike Xavier, their opinions and actions come from a natural uncertainty in the face of the Crisis. In the face of a Council that opened the gates to heresy in the Church, naturally there will be questions over whether or not the new rite promulgated and the Popes who promulgated it are actually legitimate. The SSPX and R&R position is effectively a lifeboat position of safety, that while it's too dangerous to reject the Pope based off speculation, there is good reason to be doubtful of the new rite and so the old one should be used to ensure a proper rite is used. It's effectively trying to guarantee you go to a valid mass without completely severing yourself from the Conciliar Church, in case it is legitimate.
That's different from effectively saying: "The Popes who promulgated the Novus Ordo were definitely valid, Novus Ordo and Vatican 2 were definitely valid, but in spite of being completely valid the new rite is somehow less holy and grants less graces(a borderline heretical opinion to hold about a mass you consider valid), so I'm going to go to unapproved masses said by priests without ministry under Bishops who have been excommunicated."