I'll watch when I have a chance, but Bishop Sanborn doesn't have a leg to stand on, since his ecclesiology is the same as that of Vatican II.
Bishop Sanborn has stated that Jews and pagans can be saved.
Consequently, they're formally part of the Church while being materially separated, separated brethren if you will.
Consequently, the notion of a formally united Church seeking material unity (i.e. materially divided) is the Sanborn=Vatican II ecclesiology (the subsistit ecclesiology whereby the formal+material core "subsists in" the Catholic Church, with there being all the while pieces that, while formally united, are yet in varying degrees of material separation from it).