Also, those in Al Qaeda who knew might have been killed in Afghanistan, or are trapped in places like Egypt and unable to move around. Also, it is quite possible that some in Al Qaeda DID know where things are, but they are prevented from getting there by the presence of our military, and announcing where the WMD's are is asking for an attack.
In addition, we might have moved certain items and do not want to let bad guys know of the new location.
I am possibly wrong, but you certainly have not proven your case.