Philip Zelikow replied to Glenn Greenwald:
Not sure of course what the AG had in mind, although the most important signals intelligence leads related to our report -- that related to the Hazmi-Mihdhar issues of January 2000 or to al Qaeda activities or transits connected to Iran -- was not of this character. If, as he says, the USG didn't know where the call went in the US, neither did we. So unless we had some reason to link this information to the 9/11 story ....
In general, as with several covert action issues for instance, the Commission sought (and succeeded) in publishing details about sensitive intelligence matters where the details were material to the investigative mandate in our law.
So basically it does seem like the AG made the story up. Again, to my mind it sounds like it could have been a poorly phrased hypothetical, but in that case it was an incorrect reading of the law. So Mukasey deserves the challenges he's getting on this even if it is coming from a rather odious character like Greenwald.