Obviously you’re not ready to accept his demand that the SSPX and not other group publicly criticize the pope.
Nor are you ready to meet his demans that there is no higher Magisterial teaching than him.
Nor are you ready to meet his demand that you accept Vatican II as an authoritive ecumenical council.
Therefore, you are comfortable if he proceeds to the next step which would be to declare you a heretic?
I would be very uncomfortable with that prospect.
By the way, the Pope does not have to speak ex-cathedra to exercise his magisterial authority. Magisterial means his teaching authority. It comes from the Latin word, Magister = Teacher.
In the demands that he is placing on the SSPX he is teaching not only the SSPX, but all Catholics what is expected of them in regards to the Pope and the Council. Sounds pretty Magisterial and Authoritative to me.
The fact that he says that the SSPX must lay down the claims to higher magisterial teachings than his, pretty well defines the boundaries of the game. If pretty well says that only he can decide what is good for the Church today.
I would not want to mess with this kind of authority. Whereas, the Bishops of SSPX, though they are bishops and should be respected and treated as such, do not have this kind of authority to demand respect, obedience and fidelity of the Univesal Church, only in their dioceses if they had one.
JR