"...The invocation of executive privilege could fuel suspicions that the White House is stonewalling the panel in order to cover up politically embarrassing mistakes..."

This is a red herring. No mistakes were made on Sept 11. The most surgical of all possible strikes was carried out on American soil with precision. Presidential access codes were involved, NORAD was deactivated for the event, etc. It's not that Bush 'should have known' or 'had prior knowledge'....they did the job. The Pentagon and the Bushes. The media keeps telling us the govt made a 'mistake', and that's not true. But some attention to the matter is better than none. Bush will either die on a gurney after a fair trial, or he'll throw out the 22nd Amendment and be potentate for life.