You asked why not show the contents-
Here's what he said:
This discretion is normal for any important proceeding; it ensures the seriousness of it. It so happens that the Doctrinal Preamble that was delivered to us is a docuмent which can be clarified and modified, as the accompanying note points out. It is not a definitive text. In a little while we will draw up a response to this docuмent, noting frankly the doctrinal positions that we regard as indispensable. Our constant concern since the start of our talks with the Holy See—as our interlocutors know very well—has been to present the traditional position with complete loyalty.
Discretion is required on Rome’s part also, because this docuмent—even in its present state which needs many clarifications—runs a great risk of arousing opposition from the progressives, who do not accept the very idea of a discussion about the Council, because they consider that this pastoral council is indisputable or “non-negotiable”, as though it were a dogmatic council.
Despite all these precautions, the conclusions of the meeting of the superiors of the Society of St. Pius X in Albano on October 7 have been divulged on the Internet by various yet consistent sources.
There is no lack of indiscretions on the Internet!
It is true that this Doctrinal Preamble cannot receive our endorsement, although leeway has been allowed for a “legitimate discussion” about certain points of the Council. What is the extent of this leeway? The proposal that I will make in the next few days to the Roman authorities and their response in turn will enable us to evaluate our remaining options. And whatever the result of these talks may be, the final docuмent that will have been accepted or rejected will be made public.
You may not like his reason, but he gave it nonetheless.