So, I think all this talk about "opinion" is founded either on emotion and a false understanding of humility, or else on a lack of understanding of what constitutes certain knowledge vs. opinion.
Hardly. Many of those who reject sedevacantism reject it for theological reasons. You speak as if it was theologically certain that sedevacantim is true, some people just can't figure it out. The reality is that sedevacantist thesis has very serious problems, such as Apostolic Succession (according to SVs there are no more bishops with ordinary jurisdiction in posession of Episcopal sees - you have been destroyed recently in a discussion on that topic), inability to prove that V2 Popes were formal heretics (the most you can prove is material heresy), or the fact that there were heavy weight theologians who did not believe that a Pope formally loses office without any declaration immediately after becoming a heretic.
The Church teaches that we are to treat one who
appears to be a public heretic as one as we only judge exteriors. We are not called to judge the culpability or inner workings of their minds. That should be obvious. The distinction between formal and material does not have to be made as one who claims ecclesiastical office cannot use ignorance as an excuse and the Church teaches simply that a public or manifest offices cannot hold office and Divine Law tells us the same. Apostolic succession is separate from whether the devil is the Pope or not. The one is quite easy to see for those who are objective and accept divine law and Church teaching and canon law on the topic.
Perhaps you can start a thread on Apostolic succession. I believe the hierarchy is where it appears to be, with the traditional Bishops. With the ones who continued the Church, the ones who provide the Sacraments, Bishops and Priests, seminaries, schools for children, everything the Church has always provided. History shows that Bishops have been consecrated and had ordinary jurisdiction during interegnums of the past having the tacit approval of the Holy See. This historical fact cannot be denied.
Show where we can accept a public heretic as Pope.
Show me where we do not have to submit to what he binds on the Church.
Neither of those are opinions whether you like it or not.