I think possibly Bp. Strickland may have said something in his defense.
SSPX hasn’t said anything of which I know.
SSPV? Don’t know. Last What Catholics Believe, Fr. Jenkins made some surprising (to me) and confusing statements pertaining to Vigano, Williamson, and Archbp. LeFebvre.
Resistance Bps? Perhaps. At least Bp. W. mostly agrees with him. Is it certain Bp. W. conditionally ordained and consecrated him?
Bp. Sanborn supports him, at least does not think he’s in schism because the rulings of someone who is not a pope are meaningless.
My opinion, for what little it’s worth, is that the excommunication and declaration of schism are invalid, whether Francis is Pope, antipope, just a priest or just a layman. If pope, it’s unjust and against the Faith. If any of the others, it’s like being fired by someone for whom you don’t work! Or a the lady in my old chapel who told me I was excommunicated for attending Bp. W.’s anniversary celebration! Sort of ridiculous, no? She later clarified I wasn’t excommunicated from the Catholic Church, but from the SSPX. That’s also ridiculous. Lay people do not “belong” to the SSPX. And even if someone who does belong to the SSPX, like a priest or Bishop, doesn’t get “excommunicated” from the Catholic Church. He gets dismissed? expelled? from the priestly fraternity, not from the Church. Not one person in the SSPX has the authority to excommunicate anyone from the Church. It’s certainly possible for someone, SSPX member or not, to excommunicate himself from the Church by committing certain sins, but voluntarily leaving or getting thrown out of the Society isn’t one of them.