Yes a memo can be looked at and said to contain someones name and position as a point of evidence.

However is does not limit reality to that this is the only means of gaining knowledge of the same fact.

It would be reasonable to assume that high level state department people would be in contact with intel sources related to wmd and nukes in particular, since they a issues of valid government concern.

It is not necessarily true that every person to person contact link and knowledge has to be documented.

Joe Blow at state may know Karen Dillpickle at the interior department by some means and it is never documented anywhere.

Heck may Armitage even met Joe and Val on the party circuit, who knows how he may have come across the info. Lots of possibilities.