I am not taking it as that and no one should, there simply aren't any women in the military in the films. I know the posters were done for sex appeal but it would mean that there would have to be some women in the military otherwise the men would know better.
I understand what you are saying though. The Empire was a very sexist and speciest entity and you had to be marginally better than the men or humans to be accepted into it and promoted, early works in the EU proved this with Daala, Thrawn and Issard (spelling?). The video also showed only one female and her flying was amazing when she was flying on that asteroid or whatever and it was really narrow. I wish I could watch the video again to refresh my memory but it was taken down.