Mormonism and Church discipline/Publicizing excommunication
Why does the Church not publicize the reasons for excommunication of a specific member?
The Church does not usually publicize the reason for one's excommunication. This is done in order to protect the privacy of the individual, and give them a chance to rectify issues so that they can eventually come back into full fellowship. The purpose of excommunication is not to humiliate the individual in a public forum. Those who sincerely want to return to the Church are given the chance to do so without having to endure public scrutiny of their past sins.
Individuals who have apostatized, however, sometimes use their excommunication as a means to gain publicity. They may have their own reasoning as to why they were really excommunicated, and this is what they communicate to the media. Since the Church remains silent on the real reason for the excommunication, the subject of the proceeding may spin the story any way that suits their purposes. Some excommunications have even been used to generate publicity in order to sell items such as books (or in one case, a calendar).  
- [note] Louis Midgley, "The Signature Books Saga," FARMS Review 16/1 (2004): 361–406. off-site PDF link
- [note] Mormons Exposed Launches 2009 "Men on a Mission" Calendar: Excommunicated Mormon Defies Church, Releases 2009 Edition, The Wall Street Journal Digital Network, Oct. 2, 2008.