I don’t want to get bogged down on whether or not the Church actually DOES “advocate censorship” - that’s such a broad accusation. However, let’s assume that it does for a moment:
Simply, the ultimate goal of the Church is the salvation of humanity and the glorification of God. Terrestrial freedom is a lovely thing, but many men and women have gone to Heaven without the luxury of liberty. The church espouses freedom insofar as is consistent with its moral teachings - that is to say, while it holds personal freedoms as a very good thing, it is not an immediate concern of the state of men’s souls.
It’s a novel idea for us, who have enjoyed living in countries where, for the most part, doing and saying literally whatever you want is vaunted as an objective good. This is entirely the reason why Western thought so quickly condemns “institutional religion” as being overly restrictive and moralistic - the new morality is freedom. Ultimately, however, the Church advocates certain moral truths and condemns their antitheses - and, logically, advocates the promotion of the truths and condemns those who promote immoral or unjust agendas.
Of course the Church, which advocates a certain moral doctrine, is opposed to the dissemination of information contrary to that doctrine. As an American, I can say that my opponents’ ability to proclaim their opinion is proof that my country’s open forum for free thought is still working. I do not, however, think it is morally right for him to spread falsehood. Moreover, the freedom to spread falsehood as protected by American law is a consideration for me as an American citizen; it has no claim on the conduct of the Church, whose principal consideration with regards to speech is the promotion of truth.
If the concern is that “censorship” prevents honest discussion about what IS morally right and wrong, then for the most part you’re several hundred years late. The teachings f the church as we see them are merely the conclusions resting atop years upon years upon years of debate; the Church’s history is characterized by nothing if not by internal and external dialogue. Most of those debates were resolved satisfactorily; some resolved less favorably by schism; others continue to this day. The Church has never, to my knowledge, advocated silence on a subject it itself sought the truth about; any “censorship” involved what it deemed to be open and shut topics, even if those topics were later reopened.
Again, I have not read Pius IX, but I feel that saying “the Church advocates censorship” is a pretty broad statement to make, especially when “censorship” is the sort of word usually levied at communist China or North Korea. It’s a buzzword, a trendy handle with too many modern connotations to be used gracefully in this context. If we say, however, that “the Church advocates stopping what it judges to be deliberately misleading or harmful information,” well, yeah. Find a state, organization, or religious institution that does the opposite. As others point, out, even freedom of speech in America is preserved within a context that rules out TOTAL freedom of speech, for the protection of its citizens. Unlike the United States, however, the whole point of the Church is to provide unambiguous moral and spiritual guidance, not carte-blanche license to do whatever.
Also, at the tremendous risk of sounding pompous, in discussing the ways and means of a millennia-old, billion-person-strong religious institution with centuries of thought by some of history’s greatest minds to define and defend its substance and, by its own account, the very providence of The Lord God Himself affirming it, the last person to turn to for a supporting quote is George R.R. Martin.