The whole story about "withheld intention" is a distortion of something Bp. Thuc said that does seem to be true, where he expressed regret for having consecrated the Palmarians due to their fall from the Church later on.
But someone who thinks "I should not have done that" and "I did not do that" are two equivalent statements is a bit dense in the head, obviously.
Yes, this.
What tom is missing is "the times."
To have trad bishops ordaining trad priests outside of the conciliar church was one thing, but to be consecrating bishops, well, for trads of those days, that was something that was confusing, believed to be gravely wrong - and it was essentially unheard of in the mid 1970s and 80s. Among most trads that heard of +Thuc doing such a thing, he was thought to be crazy, scandalous, senile, or whatever. Rumors abounded, many rumors were ridiculous, often they were wild and all over the place.
Those who believe +Thuc withheld proper intention simply and wrongfully believe one of those old, wild, ridiculous rumors, but apparently there's no correcting them.