Does R.Elyashiv have authority to ban books and legislate for all Jewry?

The religious community has been faced in the past few years with a new fashion- Book bans. Various blogs have posted on the issue, the latest R. Harry Maryles with an eloquent letter by an anonymous perplexed Jew who has had his Emunah shaken. Fundamentally we need to ask whether any Rav can prohibit a book on the world Jewish community or is he restricted to his Kehillah. The other issues are whether hashkafah can be legislated, especially if it does not deal with the fundamentals of Judaism such as God's existence, providence, Creation, Torah Min Hashamayim etc... Every one of these fundamentals per se has a wide range of interpretation. What are the parameters that one is bound by? As we talk about it we can already appreciate the difficulty in legislating something that broad. I would suggest that any opinion that is within the confines of the two extreme opinions of Bona Fide Rishonim and does not touch on Avodah Zarah, which is quite clearly legislated and narrow, should be tolerated. Although I have not read R.Slifkin's books, I am familiar with the subject he deals with and the sources he used to develop his ideas. The excerpts of some of his writings that I saw are nothing new and pretty much old hat.

But coming back to the issue of banning, can Rav Elyashiv or any other Rav prohibit something for the whole Jewish world? Here is Rambam in his introduction to the Yad

וכל בית דין שעמד אחר
התלמוד בכל מדינה ומדינה וגזר או התקין או הנהיג לבני מדינתו, או לבני מדינות--לא פשטו מעשיו בכל ישראל: מפני רוחק מושבותיהם, ושיבוש הדרכים; והיות בית דין של אותה המדינה יחידים, ובית דין הגדול של שבעים בטל מכמה שנים קודם חיבור התלמוד.
לפיכך אין כופין אנשי מדינה זו לנהוג במנהג מדינה אחרת, ואין אומרין לבית דין זה לגזור גזירה שגזרה בית דין אחר במדינתו. וכן אם למד אחד מן הגאונים שדרך המשפט כך הוא, ונתבאר לבית דין אחר שעמד אחריו שאין זה דרך המשפט הכתוב בתלמוד--אין שומעין לראשון, אלא למי שהדעת נוטה לדבריו, בין ראשון, בין אחרון. ודברים הללו, בדינים וגזירות ותקנות ומנהגות שנתחדשו אחר חיבור התלמוד

Clearly without the Beis Din Hagodol, without the authority of the Gemara and even if we accept the authority of the Beis Yosef in Shulchan Aruch,( this is a separate issue that is not as clear as one might assume - vide Rema, Gra, Brisk etc...), there can be no universal Psak on anything that is not clearly legislated in the Gemara. Rambam legislates based on his understanding of the Gemara's decision and the arguments among the Rishonim revolves around their disagreements on each of their own understanding of the Gemara but to go beyond that and try to impose a universal law, I don't think is tenable. R.Elyashiv is entitled to issue all the bans but we are not obligated to follow if we have either a local Rav's support or even an honest conviction that he is wrong.

The tendency in the community has been to exaggerate the authority of the great halachist of our times. It is grounded in the need to inculcate Kevod Hatorah in the masses. The same can be accomplished by retaining the autonomy we have in our current status without a Sanhedrin. Exaggeration brings with it the risk of disappointing, and weakening the Emunah of the disappointed.