So the only reason they're doubtful is due to "the intentions of the ministers"?
That's what bugs me about +Lefebvre, +Williamson, Hewko, Ruiz and the SSPX.
There are very objective reasons to believe that the NO sacraments are invalid, but they decide to make the basis of the doubt this subjective thing (the intention of the minister).
Even worse, they claim that the validity, say of a conferred holy order, must be assessed "case by case". What do they mean by this? Do they interrogate the bishops to see how catholic they felt the day they conferred the order?
"
And which of you by taking thought, can add to his stature by one cubit?" - If a man does not have the supernaturally conferred episcopacy on his soul, he can't do anything even if he's maxed out his theological virtues that day.
There was a case of +Tomás de Aquino defending some "priest" in Brazil, ordained by the Novus Ordo and NOT conditionally ordained, who I understand worked with the resistance there. There's an audio on YouTube of the bishop defending the priest but I can't seem to find it now.