There's a difference between an FSSP priest being ALLOWED to concelebrate the Novus Ordo, and his being FORCED to concelebrate said Mass.
Read the article carefully. The infamous Protocol 1411 clearly violates the original agreement between the Vatican and the Fraternity, which guaranteed them the EXCLUSIVE use of the 1962 Missal. Remember that the FSSP was set up by the Pope in order to bring SSPX priests back to the fold. Because of the outrageous actions of 16 French priests, who were upset over the outcome of the Fraternity's general election, all FSSP priests may someday be REQUIRED to concelebrate the Novus Ordo by their bishops. Once this door is opened, there is no telling what additional requirements may be imposed on the Fraternity, such as an obligation to celebrate Sunday Masses in under-staffed parishes, for example. This will, IMO, be the death knell to the Fraternity, and a further disincentive for SSPX'ers to come back. Hey, come back to Rome and then get stabbed in the back.
And the Vatican's heavy-handed shakeup of the Fraternity, and its cancellation of their general chapter, sends the usual chilling message to traditionalists:
"Watch your step, or we'll come down on you like an ton of bricks!"
Funny how apostates and heretics continue to flourish in our chanceries and "Catholic" colleges, while traditional Catholics set off a red alert if they so much as step out of line.
That's against canon law. Cardinal Hoyos says in his letter to the General Chapter:
On the other hand, it is clear that no priest is obliged to make use of this right. In this way, an atmosphere of freedom and trust can arise in this area, which stands in opposition to every exclusivity and every liturgical extremism. The "Fraternity of St. Peter", as its name already says, can only be a family of brethren, who mutually accept each other with fraternal love, and who are united wholly into the great family of the Roman Catholic Church, where there is a legitimate place for Catholics with a traditional sensibility, which I will defend with all my power.