I was previously on an academic treadmill. It was more or less assumed that if you were capable, you wanted to be a professor. It took awhile before I could really see the pros/cons of tying my research to that particular structure.
I think a lot of women -- highly competent women -- are stuck in similar treadmills -- Law School, Finance, Consulting, Grad School. If they're not presented if this alternate life path, it may take many more year for them to get started.
And that may be when they have a family, and that may put a damper on startup ambitions.
Absolutely people have the right to make their own choices, and it's possible that different genders/families/ethnicities/what-have-you will make statistically different choices.
But I really don't think we are doing such a great job with presenting women, or the population at large really, with the full range of what's possible. There are a lot more people out there who would be happier doing a startup, or any kind of entrepreneurial endeavor focussed on something they are really passionate about, than are actually doing one.
There's really a lot we can do in this arena, and I don't think this industry's exhortations or encouragement really represents some kind of dismissal of women's choices or co-opts free will.