To be fair, that press briefing was in the East Room of the White House, which is traditionally not decorated with any American flags.
There are more important things to worry about in regards to zero than this.
Bush didn't seem to have a problem finding room.
http://georgewbush-whitehouse.archives.gov/news/releases/2005/04/images/20050428-9_web012t4778bjpg-515h.html
President George W. Bush holds a press conference in the East Room Thursday, April 28, 2005