Just guessing, but I would imagine the reason given is that advancement in rank is hindered by a lack of combat experience, so keeping women out of the front lines is a way of discriminating against them.

And complicity, i.e. getting people to squeeze the trigger and actually kill for the enrichment of the already obscenely over-rich, is the best way to ensure loyalty. With women in positions of authority in the corporate world it's important to make sure they have as much reason as men to be patriotic.