A non-US National can only join the US Military as an enlisted serviceman - not as a Warrant or Commissioned officer.
The guy in question was a member of the US Army, have a copy of the 1972 US Army Register, he joined up 29 Apr 69, made WO1 24 Aug 70, made temp CW2 20 Aug 71, just don't know where he served, it certainly wasn't with my unit as he states.