I’m guessing the files don’t actually contain much about the justices but more about the DoJ and the people who work there.
I could be wrong.
It may be that some clerks are assigned to collect all negative information—proven, speculative or false—on each justice that is published on the Internet. This might be done so the justices can periodically look at what is being said about them. Anonymous may have these files. But I'm just guessing.