I do think you exaggerate about sedevacantists calling people heretics for not being sede, simply because they ask questions.
Based on this site, it's no exaggeration. This last week, i've seen the use of the word 'heretic' more than the last 6 months.
Where the heresy comes in is in denying the indefectibility of the Church and claiming that the Papal Magisterium and the Mass of the Catholic Church can become corrupt, so much so that Catholics are require to break unity with the hierarchy to remain Catholic. That is in fact heretical.
Again, no Trad disagrees with the above, in theory. But in practice, it's difficult to explain, because...we Trads aren't the Church.
Where the disagreement comes in is on the definitions of 'indefectibility' and 'papal magisterium'. Sedes argue as if the problem is easy to understand (but that's because they already have a pre-conceived solution). R&R (not +Fellay's R&R, but +ABL's) see the complexities of these mysteries (since, ultimately, they are of Divine origin) and see the problem as more nuanced.
Most sedes want a black-n-white answer to a complex problem, which is short-sighted. ABL's style of R&R is an overly-complex answer to a complex problem...the evils of analysis paralysis.
I don't understand why such R&R don't consider Fr. Chazal's sedeimpoundism.
This generation of Trads will never agree. The divide between "The Nine" and the sspx/Resistance is too great. It will take a Catholic pope, or some great persecution, to get people to come to their senses and work together.