Actually if you think about it your logic is totally flawed. What enables guys to ski well switch is the same thing that enables us to ski better regular. To keep your tails up skiing switch at higher speeds what do you? Lean foward, something you already acknowledge that we can physiologically do better.
Girls can't ski switch as well as guys for the same reason they can't ski regular as good as guys, it's simply the badunkadunk, the junk in the trunk. You have to weight your tips to ski either way and our asses just do that better than theirs.