Schism means to separate oneself from Communiom with the Church. +ABL and the Bishops willingly got themselves excommuniated by going ahead with the consecrations.

Yes, +ABL separated himself from heretics. We should have no desire to be in communion with people who don't possess the Catholic Faith. He separated himself from the Conciliar heirarchy, not the Catholic Church.

But to one who believes the Conciliar hierarchy is the valid hierarchy, that's a problem. Good luck trying to explain that to Xavier though. At least the other sedeplenists have some sort of explanation to try and reconcile the seeming contradiction there, but Xavier not only accepts Francis as Pope, but he also accepts Vatican 2 and the validity of the NO. He has no explanation, and believe you me he's been asked many times, for why he continues to go to Masses said by Priests with no canonical status when he recognises the NO rite as valid. He just gives some line about how the NO grants less graces despite being valid, which is itself a borderline heresy even if you ignore his act of schism.

That's where it gets complicated (conciliar hierarchy). I believe they hold their offices materially. But then again, I have zero theological training. I desire to keep the Catholic Faith in order to be saved, and adhering to V2 heterodoxy and heteropraxy jeopardizes that. 
I'm new here so I don't know all details behind Xavier. Is he an SSPX seminary? 
If he accepts V2 novelties as legitimate doctrine and the New Mass as legal and licit, why in the world does he support the Society? I think you would be correct in saying it is an act of schism to accept Vatican 2 and the New Mass as legitimate acts of the Church, but at the same time resisting them by adhering to a group who rejects them. Cognitive dissonance.