It's a matter of perspective. I would expect points #3 ("avoid the claim to a Magisterium superior to the Holy Father") and #4 ("respect for the authority of the Vicar of Christ") are tantamount to muzzling from the POV of an SSPXer.
They'd consider #3 "muzzling" because AFAIK the SSPX believe in some standard outside of/beyond the current/unbroken Magisterium held by Rome. #4 is "muzzling" because the SSPX believe the current Pope lacks authority, due to their fundamental disagreements over the issue of an unbroken chain of authority from earlier popes.
SSPX is NOT sedevacantist; what on earth (or in heaven) are you talking about?
A MESSAGE FROM BISHOP FELLAY
Superior General of the SSPXJuly 2006
At the end of October, the Month of the Rosary, the Society intends to present the Holy Father with a spiritual bouquet of a million Rosaries.
The Rosaries will be offered for the following intentions:
- To obtain from Heaven for Pope Benedict XVI the strength necessary for him to completely liberate the Mass of all Time, called the Mass of St. Pius V.
- The restoration of the Social Kingship of our Lord Jesus Christ.
- The triumph of the Immaculate Heart of Mary.
We are calling you to a veritable Rosary Crusade. This prayer, so often recommended by the most Blessed Virgin Mary herself, has been presented as the great means of support, protection, and salvation for Christians in this time of crisis. For centuries, ever since the antagonism between the world and the Church began to grow more intense, this prayer has appeared as the weapon given us by Heaven by which we may defend and sanctify ourselves, and conquer.
We thus earnestly recommend that you begin without delay to bring spiritual roses to our bouquet.
We also desire to manifest to both the Roman authorities and Heaven, by this obviously symbolic quantity, our will and determination "to pay the price."
Link.
You may be thinking of sedevacantists, a different stratum altogether.