He worked in secret for months. It wasn't until Sessions decided to tell people about him that his name became public. Other than those paying close attention, most haven't grasped how telling that sequence is.
Sessions was the one who told the world about Huber. AFTER Huber had already been working for months - without a word of his work leaking. That's OPSEC, anons. Sessions let the cat out of bag about Huber because he was beyond being stopped at that point.
Here's the best part. Horowitz and Huber were working together all that time in secret as well. Without a filter. If you notice in the OIG report, the body is very different from the conclusion and summary. The body is filled with facts and evidence without opinion. Those facts have already been fed to Huber (in addition to more facts that were withheld for purposes of protecting ongoing grand juries as Q alluded to). Huber doesn't care about the summary and conclusion - he cares about the facts he can use to build cases.
Checkmate already happened.