In terms of the pure neurophysical ability to do it, I don't doubt for a minute that the percentage of women capable of killscreening the game is about the same as the percentage of men.
When it comes to sports and games where the physical dimorphism between men and women does not put women at a disadvantage (chess, video games, etc., as opposed to football), women have demonstrated that they can dominate. For example, Jennifer Harman, Kathy Liebert, or Vannessa Selbst will destroy virtually any male poker player.
The snag in all of this is participation.
In competitive games, the ratio of participants is always so heavily weighted towards men that the lack of women at or near the top is statistically inevitable simply because far more men are playing. (Classic arcade gaming in particular is a major sausage fest, probably like 200-to-1 male to female.)
So it's not that women aren't or can't be as good, it's just that very few show up to play.
As for the difference in participation, that I think comes down to anthropology.
Men are different than women in terms of (1) psychological hardwiring and (2) social programming as it relates to obsessiveness/drive, risk-taking, and competitiveness.
Decide for yourself how much of it is nature and how much is nurture, but whichever it is, the bottom line is that men (on average) just care about this kind of stuff more.
Finding a woman who *can* killscreen DK is easy. What's hard is finding one that's as crazy as we are about *wanting* to do it!
If participation by women were to increase, if we had even 10 going for a kill screen, I think it would happen very quickly.