I don't want to sound like a conspiracy nut, but I kind of get the feeling that all of the sensitive files pertaining to the JFK, RFK, MLK, 9/11 crimes have been treated in like manner.
By the way, did you know that a large number of Government files pertaining to the Japanese 'surprise' attack on Pearl Harbor way back on December 7, 1941 are still sealed? Why do you think that is?
https://www.youtube.com/watch?v=aDtz3aPgWwE