It seems to me that the legislator is misrepresenting the argument for charging young men more than young women. The argument is that insurance companies calculate risks based on statistics they gather about groups. Even though the brother and sister are exceptions to the generalizations, the generalizations about dangerous driving are statistically sound, and when calculating risks it is reasonable to rely on generalizations. You are unlucky if you are an outlier in your group, but the existence of an outlier doesn't make it wrong for the insurance companies to use the best statistics they can gather. Whether or not you agree with the conclusion about relying on generalizations, the point isn't about gender at all. It's about how to calculate risk and whether insurance companies should be entitled to charge individuals more if they are in a high-risk group. If we assume that insurance companies are permissible, then I can't see how they can not rely on generaliations, since they wouldn't be able to function otherwise. As far as I can see it, there is no double standard, stereotyping, or sexism here and the legislator is misguided.

On the latter set of questions you raise, it is a common complaint against feminism that it simply reverses the historical devaluation of women and instead values women at the expense of men. I see no evidence of this in the example or in the broader feminist movement. If you think it is true, then it would be interesting to discuss a different case.