I think this has Sokolov wrong: he isn't a punchclock villain, he is a soldier. Good soldiers are supposed to distinguish combatants (kill as fast as possible) from non-combatants (protect as much as possible). He has carried this world-view over into his civilian career; he classifies anyone willingly involved in the underworld as a combatant, and is determined to help Zula because she is the only person in the group who is not a criminal.
I think this has Sokolov wrong: he isn't a punchclock villain, he is a soldier. Good soldiers are supposed to distinguish combatants (kill as fast as possible) from non-combatants (protect as much as possible). He has carried this world-view over into his civilian career; he classifies anyone willingly involved in the underworld as a combatant, and is determined to help Zula because she is the only person in the group who is not a criminal.