Women and trans people, if they want to serve, should serve as non-military civilian employees.
Military training is expensive. The purpose of giving it to all recruits is so that, when it hits the fan, those military people doing clerical, supply, etc jobs in the rear, can be moved to the front to fight. If you staff those jobs with people who CANNOT be reassigned to combat, then you LOSE that reserve capacity which might be critical to winning the fight.
You make a valid point! :-)