That was between him and the USOC, obviously that's not enough. The USOC should have assisted him with his medical exemption application if proper grounds existed, after the competition and after testing positive it's much too late for that. At that point the USOC could still have taken responsibility and demonstrated that it was their fault and not the fault of the athlete like had happened a few months before in hockey at the Winter Olympics with Germany's Alois Schloder, but they didn't take responsibility and so DeMont's ban wasn't overturned.
The WADA was founded in 1999, so they had no role in the 1972 Olympic testing.
The NHL's testing policy has always been a joke by the way (and didn't exist until quite recently), everything is agreed between the league and the NHLPA and neither side has any interest in ending up with many cases. At the time when Pound gave his comments, players couldn't be tested during the offseason or the playoffs at all, even now that remains limited. Maybe usage was more common in the past, but there will still be many enough guys like Jarred Tinordi or Nate Schmidt that try to do it in the shadows built into the system.