Earlier quoted context omitted.
The only sexist thing here is your support of a baseless claim. If it's not baseless, presumably you have something to offer. However, without evidence, you are most likely wrong. Does that wrongness amount to sexism? Hard to say; my inclination says yes since you're referring to shuffling hundreds of dimensions defining employment into "life choices". Yes, that is probably a factor; culture is a powerful force. But…
The only contention I have is one you agreed to elsewhere: that the actual aggregate wage-gap once you've controlled for common variables (such as life choices) is 3-6% (with women earning more in some fields), which likely isn't significant or correctable. A difference on that magnitude can easily be something about aggregate behavior correlated to sex, an uncontrolled for variable, or just random chance. So let me…
However, there is abundant evidence that there's a systemic divide in opportunities. This is easy to see in the aggregate and particular. That is the interesting thing in itself: if we could be assured that the gap could sexist solely for life choices, this wouldn't be an interesting topic. That's a devilishly hard thing to argue for, however, so id prefer to move forward as a society assuming that we can do more to expose opportunities to everyone, assure that people are protected in their right to follow opportunities, and that we can demonstrate the effect of the policies at moving toward an ideal of equal pay.
If we can't move towards that, perhaps our ideal, well, isn't what society wants. I doubt that we've even approached that level of confidence in our support of communities subject to subtle bias difficult to divorce from "life choices".