I agree with RYTX... There's really no reason (since the war ended fairly soon after that incident) to think that females in the rigidly structured Andalite society could advance very far in the military...
Also, Estrid was an extremely talented and well connected Andalite female, but she was still only an Aristh... And look at what she had already overcome... Massive sexism not just in the military, but in the scientific community as well... It is unlikely that anytime in the near future (even with the necessities of the short-lived rest of the Yeerk conflict) Andalite females would branch out to the male-dominated spheres of society... (America took like, 75 years to make that kind of progress AFTER an organized women's rights movement began...)