Actually, most of the Purple decrypts transmitted to President Roosevelt particulary from mid-1941 on were delivered to President Roosevelt by Ensign Schultz of OP-20-G by hand and not through the mail by Lt. Cmdr. McCollum of the Office of Naval Intelligence. Originally, these messages were transmitted to Roosevelt on alternate days by the Army's cryptologic agency, SIS, and OP-20-G of the Navy. However, the Army found one of their decrypts in a waste basket at the White House and refused to deliver any more to FDR. Therefore, the Navy that is OP-20-G (not ONI) took over and hand delivered them on both even and odd days of the month.
In order to further his revisionist conspiracy theory, Stinnett implies a much closer relationship between ONI and OP-20-G than actually existed. Thus, he invented a nomenclature that did not exist, namely "Station US." McCollum was a part of ONI then called OP-16 headed up by Captain Anderson, while OP-20-G under Captain Safford was a part of Naval Communications. Actually, OP-20-G was also referred to as "Station N" or sometimes internally as "George", the then flag phonetic for G, but never as Station US. Of course, Station US was never a substitute for ONI or OP-16.
You seem to have glossed over my comment that Captain Kirk's response to Lt. Comdr. McCollums so called "Eight Point" memo indicates that it may not have been forwarded on to Captain Anderson at all, but returned to him without such forwarding. In naval correspondence, such and endorsement would normally have started out with "1. Forwarded (with any qualifying comments). The absence of such a forwarding endorsement to me, strongly suggests it was sent back to McCollum with Captain Kirk's listed comments and never got to Anderson much less to FDR as Stinnett unashamedly contends.