If one accepts Luther’s canon, then one has certainly accepted Luther’s infallibility and authority, i.e. a pope.
What I believe Protestants fail to grasp is that the Catholic church is not static and within its ranks there is still debate and dissension. There has been since the beginning.
What that means is that Catholics often wander off the reservation and into territory that is heretical, but until and unless a doctrine is declared as binding it is not an official.
For example there is still debate on the ordination of women, but JPII has declared that the Church has no authority to change what Jesus sanctioned and instituted, namely a priesthood of men. Therefore, the debate may rage on and “Catholics” may dissent from the doctrine, that dissent keeps them from full communion with the Church, i.e. heretics.
Scripture Canon has been defined and reaffirmed by the Church. Catholics who wish to be in communion with the Church must accept that.
Now, many will use the early Fathers and Doctors to support their protestantism, saying well Jerome said this and Augustine said that. But, neither, in fact, none of them, were pope and had not the authority, the keys, as given to Peter and passed to his successors, to bind or loose.
That is the beauty of the Church, that under the guidance of the Holy Spirit, she sifts all theologies and in so doing, separates the chaff from the wheat. That is why we Catholics can trust what she doctrines declares as Truth.
If one declines to accept as canon that which is of questionable provenance, one is in the company of numerous early Church fathers as well as quite a few figures within the Church right up to the Council Of Trent.
This is no more "Luther's Canon" than it is "Jerome's Canon." The Protestant Canon is that which is incontrovertibly scripture, relying upon authority going back to the early church and even before to rabbinical sources. The Catholic Canon has become "because we say so" despite the matter being left open theologically by the aforementioned Council.