Wow, the 9-11 Commission is amateur hour. They can't invent even lame excuses.
Well, when you consider one of the commissioners had a key part in making sure this information never reached the FBI thanks to her "Gorelick Wall" policy, you can't expect the panel to be much more than a lame white wash drowning with incompetence.
I agree, their excuse is beyond lame and doesn't even rate "fig leaf" status.