Also, I'm certain the courts would reject this policy if women already under contract weren't grandfathered. Unless given the option to re-sign or get out, that is.
Scary to think that our courts could be so idiotic, but it is indeed possible. Lofty ideological notions about "equality" can't override real world biology. Men don't get pregnant, period. And I hate the touchy-feely nonsense of couples who tell people that "we're pregnant". Men can be "pregnant" by 100 different women at the same time, and it still wouldn't affect their ability to perform military duties.