I agree with you. That is doctrine, which cannot be changed. However, as someone who attends a sedevacantist mass weekly using the 1956 missal, i can say that I have experienced way too much vitriol, incivility, and lack of charity among that crowd. Not all, but many.  I am not a sedevacantist. I hope the pope does the right thing by bringing back the mass of the ages and phasing out the 1962 roman missal, which is technically the TLM but too vitiated to remain. we ought to go back to the St. Andrew missal of 1945 before any of the bugnini problems. 
I am actually in many ways a liberal catholic.