FBI Inspector General Michael Horowitz apparently concluded that the conduct "did not affect the overall validity of the surveillance application," which was made with the secret FISA court.
The Post article, as well as articles in The New York Times, at CNN, and in other outlets, downplayed the behavior as having had "no effect" on the FBI's surveillance of Page, ignoring the fact that tampering with a federal document is a felony. That's consistent with the Justice Department's own policy of protecting their own while wrecking the lives of those who have the guts to stand up to them.
Look at The Washington Post's original account of the inspector general's findings. The FBI attorney was just a "low-level employee" who has already "been forced out of the Bureau." The altered document "did not affect the overall validity of the surveillance application." The employee "erroneously indicated he had documentation to back up a claim he had made in discussions with the Justice Department about the factual basis for the application. He then altered an email to back up that erroneous claim."