In a newsweek article mostly about the recent shooting, this odd element was shoehorned into the last quarter of the article:
Others close to Cheney had suggested that he was profoundly affected by 9/11. It is hard for anyone who was not in Cheney's shoes that day, and in the weeks and months that followed, to appreciate the stress and uncertainty of that time. Around 9:35 on the morning of 9/11, Cheney was lifted off his feet by the Secret Service and hustled into the White House bunker. Cheney testified to the 9/11 Commission that he spoke with President Bush before giving an order to shoot down a hijacked civilian airliner that appeared headed toward Washington. (The plane was United Flight 93, which crashed in a Pennsylvania field after a brave revolt by the passengers.) But a source close to the commission, who declined to be identified revealing sensitive information, says that none of the staffers who worked on this aspect of the investigation believed Cheney's version of events.
A draft of the report conveyed their skepticism. But when top White House officials, including chief of staff Andy Card and the then White House counsel Alberto Gonzales, reviewed the draft, they became extremely agitated. After a prolonged battle, the report was toned down. The factual narrative, closely read, offers no evidence that Cheney sought initial authorization from the president. The point is not a small one. Legally, Cheney was required to get permission from his commander in chief, who was traveling (but reachable) at the time. If the public ever found out that Cheney gave the order on his own, it would have strongly fed the view that he was the real power behind the throne.
That struck me as odd... yes, the content, but also the placement.