Just because it's publicly available doesn't mean the US government won't try to embargo it. The government does silly things all the time.

The book "No Easy Day" became a New York Times best seller as soon as it was published (it's written by the SEAL that allegedly shot Osama bin Laden). The Department of Defense threatened to revoke the security clearances of military members that read the book because it contained classified details. It took a few weeks before they walked back their threats, because somehow nobody at the top realized how stupid it was to revoke security clearances over reading a bestselling public book.