Also, being single sex is not the draft's main problem. The main problem with the draft is that it is immoral.
Meh. I don't necessarily ascribe morality to it. It think it's a violation of some basic freedom of belief, sure. Mostly, I think it's a bad idea for more pragmatic reasons: People who are forced or coerced into fighting for a cause aren't particularly dedicated. I'd much rather have a force comprised of volunteers, people who are fighting for something they believe in.
In the event that a draft or conscription is actually occurring, however, I have an objection to it being single sex. I get that it's an easy shorthand sorter - one way or another, the conscripts need to be people who are moderately expendable, they need to not be leaving children uncared for. The simplistic assumption that women are care-givers and men are expendable is easy to put in place, and is probably good enough for a fast response.
I'd prefer something a bit more purpose driven. Say, a policy that stipulates that a draft/conscription cannot leave a child or a dependent without a caregiver, with no consideration to the sex of the caregiver - leave that up to the individuals involved. But that's also going to be a lot more complicated to administer. You'd have to look at families, identify single-parent households for exclusion, and for two-parent households, you'd have to put some method in place to allow the parents to select who stays with the kids and who goes to fight.
That's the kind of thing that would probably work better if it's a formalized draft registration policy that is set up and maintained during peacetime, to be enacted during wartime. But trying to do that on the fly just isn't feasible.
Perhaps a more hammer-and-nail approach: if a person doesn't have children, they get conscripted.
At the end of the day, it's all academic for us to discuss in this thread. But I do think it's worthy of some discussion, it guides thoughts on how to alter draft eligibility rules for future conflicts so as to make them reasonable and appropriate.