Who can speculate as to the actual reasons? Historical articles claim that due to Oshchepkov's refusals to deny the involvement of Judo in his creation of Sambo (as the first European black belt), he was assasinated during Stalin's political purges of 1937. (Unfortunately, "modern" Sambo appears to be just as internecine.)
I'm not sure what you mean by "bio-mechanic" flavor. However, the producer was interested in the "rugged" flavor of the outdoor training we received in Combat Sambo as per Gen. Retuinskih.
I have no idea regarding Fedor's motivations, so I can't speak to it.