> By your argument would you say that all of these are legitimate targets?
I am not your parent commenter, and do not necessarily subscribe to any of their arguments, but I can answer your question directly: yes, to some people, the conscription of all people in a certain age range does make them legitimate targets.
In particular, from my perspective, one of the primary downsides of the inclusion of women in the armed forces is specifically that it legitimizes taegetting (other) women as a military target.
So, to be explicit, if an organization I conscripts women into their military and someone else targets I women militarily, then I will hold I morally responsible for their fate. Similarly, if an organization H utilizes children as soldiers (or human shields) and other children are militarily targeted, I will consider H morally responsible for their fate. (And to be more explicit still: sucks for all the men everywhere.)