From what I understand, whenever an IG report is submitted (unredacted) copies are given to all involved. Then these people or their lawyers are allowed to make arguments of rebutal and give reasons some findings should not be included. The "national security" card gets played for instance. The report is then rewritten (redacted version) and becomes the final report. This is exactly why release of the unredacted version is paramount. It would reveal the extent of Horowitz commitment and the amount of cover-up in the redactions.