The Immaculate Conception wasn't a dogma until Ineffabilis Deus. Bl. Pius IX convened over 400 bishops in Rome to debate the issue before defining the matter - but he knew well that a dogma could never be a legitimate subject of debate.
But see? They're all over the place, the whole lot of them. This in and of itself should be more than enough evidence that, hey, we aren't dealing with a doctrine here, but theological speculations concerning difficult situations we don't understand.
You could make the same appeal about, say, the sinlessness of the Blessed Virgin, which was denied by many of the Fathers. But we know that that doctrine is part of the Deposit of Faith, and we have the testimony of Augustine and others to prove it.
Again, we have other saints and long-since dead theologians denying it.
What theologians, after Florence, denied baptism of desire? What theologians after Trent did not interpret, as St. Alphonsus Ligouri did, the Decree on Justification as supporting baptism of desire in Chapter IV?
But see the bolded part? That's not doctrine. He's saying this, yes, and it sounds cool, but the Church simply hasn't defined that.
The Church has decided that there are individuals inside the Church, although they are not members. Even prescinding from the Decree on Justification, there is the letter of the Holy Office, Lumen Gentium, the letters of Innocent II and Innocent III, the Roman Catechism... St. Pius X (Praestantia Scripturae) and Bl. Pius IX (Tuas libenter) both condemned the opinion that it is only necessary to believe infallibly defined doctrines.
This is sheer speculation. This is not doctrine. But look at this, though, in comparison to the above speculation:
Trent teaches that the Sacrament of Penance can be received by desire and so justify. If your interpretation of the canon was correct, it would have contradicted itself.