It appears to me that this is a trick. They do not want information through grand juries to become public. Mueller has nothing when compared to the evidence against other high level criminals. The crimes (the revelation of which will put some in the hospital) are set to be revealed to the public, if we can go by the 10s of thousands of sealed indictments currently in place.
Eventually, all that grand jury info would become public…..unless this sleeper case prevents it. How many decades old is this case? Why now?
https://www.politico.com/story/2018/08/27/robert-mueller-special-counsel-report-sleeper-case-797373