There are CLEARLY roles for women in SF operations like Delta. Almost solely in intelligence gathering via electronic means,but there ARE times when a undercover male intelligence operative on a scouting mission could use a woman companion to help provide him cover by walking with him as he did his scouting.
Guards just pay less attention to a couple walking by than to a lone male of military age and appearance.
They should NEVER be allowed to wear a Beret because they can NEVER hope to qualify by the same physical standards as the males. If you can't throw your 200 lb wounded teammate across your shoulders and run to safety with him,you should never be allowed on an operational team,regardless of gender,sex,or who you may be related to.