I distinctly remember at the time he said it wasn't because when it came out "we" all started doing the happy dance and shouting "in your face" at the womyn-priestette people and then cardinal Ratzinger cut the legs out from under our unChristian glee. I believe what then developed was the statement that OS wasn't an exercise of the charism of infallibility because there was no refinement or clarification of dogma, it was something we already knew and fully understood JPII was just driving home the knife... er, so to speak.
As to my non answer... well, maybe it is. I'm not positive that the statement requires the assent of the individual reader. It may be a statement of fact as understood by the Catholic Church. I am my children's father even if some of them decide to go all emo on me in the future and claim otherwise. I think we've bounced off each other on this subject earlier and I sort of wondered if the interpretation of that line was dependent upon the intent of the currently reigning pontiff.
And this is what I remembered:
"Dubium: Whether the teaching that the Church has no authority whatsoever to confer priestly ordination on women, which is presented in the Apostolic Letter Ordinatio Sacerdotalis to be held definitively, is to be understood as belonging to the deposit of faith.
Responsum: In the affirmative.
This teaching requires definitive assent, since, founded on the written Word of God, and from the beginning constantly preserved and applied in the Tradition of the Church, it has been set forth infallibly by the ordinary and universal Magisterium (cf. Second Vatican Council, Dogmatic Constitution on the Church Lumen Gentium 25, 2). Thus, in the present circumstances, the Roman Pontiff, exercising his proper office of confirming the brethren (cf. Lk 22:32), has handed on this same teaching by a formal declaration, explicitly stating what is to be held always, everywhere, and by all, as belonging to the deposit of the faith."
COVER LETTER TO BISHOPS' CONFERENCE PRESIDENTS Cardinal Joseph Ratzinger