OK can you explain where he's off, other than just saying he has no authority?
No Byz, saying +ABL sympathized with the sede belief is true, but if the picture were painted accurately, it would be painted only in the sense of +ABL being likened to a father who understood the trials of his children. +ABL taught as you quoted,
"...It is not impossible that this hypothesis will one day be confirmed by the Church.” No one disagrees with this AT ALL, except the sedes.
What Last Tradhican posted is certainly true re: it's all speculation, yet what is apparent because it is recent history, is that the priests within the SSPX who were expelled by +ABL for their sedeism (and other things stemming from their sedism) wanted no part and had no intention of waiting for the Church to confirm their hypothesis - note that this is still true. I actually witnessed this. This is the jist of the whole "+ABL went back and forth on sedeism" idea that Lad constantly promotes, which is an idea that is altogether fallacious and I think disgusts +ABL every time the idea is promoted.
These days, the turmoil within the SSPX in those days caused by sedeism is nearly *always* underestimated and understated, the confusion and chaos it caused within the SSPX was tremendous and affected the SSPX as a whole, it was plenty great enough so that if +ABL was going to give in, he would have given in right then in there, but he didn't, he never did.
Take it for what it's worth coming from one who was there.