This ban is mostly likely a reaction to the now infamous subreddit that sought to identify the "Boston Bombers" using security camera footage. The online community falsely identified a person, causing a giant media backlash against the website. The subreddit accused 22-year-old Sunil Tripathi, a missing Brown University student, of committing the attack. Tripathi's body was later found and his family voiced outrage against the accusations.
Reddit told the Washington Post earlier today that they banned the Navy Yard shooter indentity subreddit because:
it violated site rules by encouraging the posting of personal information. The quote from the side bar that subreddit that was banned said "no personal information about leads unless you are really sure." We do not allow the posting of personal information under any circumstances.
One shooter, 34-year-old Aaron Alexis of Forth Worth, Texas, has been identified as the deceased shooter in today's Washington D.C. Navy Yard shooting.