There is a big difference between the type of military you can use when you are being invaded and the battlefield is your own cities, towns, and farmlands.
If America was being overrun then females and old men would make sense, but when putting together a lean hard expeditionary force you need the leanest and hardest because numbers are limited and you need every ounce of per capita muscle and testosterone driven aggression you can get, everytime you replace a man with a female you are degrading your capabilities.
Yes, I agree. Just like that old joke about the 60 year old veteran. I can’t run so I will stay here and fight. And usually a lot better than the young guys. The old guys already survived a war.