A guess based on the Hillary emails IG report:
In that report, the summary (which was the only thing the media ever read or reported on) bent the revelations in the report almost to the breaking point, to come up with a summary conclusion that of “nothing to see her move along”.
My guess is that Horowitz did the same with this report, and contorted the conclusions to put the best gloss possible on what was revealed in the report itself.
It’s possible that some of the redacted parts of the report would kick the legs out from under the summary, but the team writing the summary felt free to ignore them because no one would ever see them.
So Barr kept his mouth shut until they finished writing everything then declassified these conflicting passages at the last second, throwing the whole summary into doubt. Do they leave it as is, even though its (now demonstrably) false? Or do they scramble to rewrite the summary to fit the facts that they knew all along but which are being newly revealed to the rest of us.
I'm not sure I will read every line on every page, but I will give it a try.
I have my own opinion, but I am willing to revise it if warranted.