Oh but it is. Only tradition says that it isn’t.
Only the Traditions of Men such as Luther and Cauvin say sola scriptura is biblical. Scripture does not.
I think the whole point is that the Pope does not want us to deny there are differences in our theologies as a means of increasing ecunemical understanding. Also in context of the speech I do not think he meant Tradition as Catholics understand it but traditional teachings on such things as sexual morality that were once universally shared by Catholics and Protestants. As well as Christian teachings stated in the Creeds and the confessions, etc of various Protestant denomination.
I say this because the Pope knows perfectly well Protestants reject Sacred Tradition as a source of revelation and have done so since the Reformation. It would be very unlikely he would think such an action as prophetic. In Protestanism (and amongst dissident Catholics) we see new challenges to the faith being made daily not by outsiders but by those within the denominations.
Calls for the blessing of homosexual unions, calls for the ordination of non celibate gay clergy. Denial of the bodily resurrection of Jesus Christ, of the Virgin Birth, of the uniqueness of Christ. The list could go on and on.
These all go against the traditions of the very Protestant denominations faced by these “prophetic” actions. That is what the Pope was addressing how in their own context Protestant churches must continue to affirm Truth and not be afraid to emphasis their own doctrines.
The Pope of all people surely knows the leaders and members of Protestant churches are not going to forsake the Reformation and its core doctrines. His call indeed is for those to be upheld. Because in spite of our very real differences the Truth of Christ and His Gospel are still proclaimed in the teaching of the Protestant churches. That needs to continue.