The analogy here is providing an option for a customer at a restaurant to select which race or gender they want serving them. Yes, definitionally, it is discrimination by sex. Especially because no one is given the option to pick a male driver, this will just result in women receiving more ride requests while they’re active and driving.
I can’t see how this would be anything but a slam dunk violation of federal law. Lyft is actively and obviously participating in discrimination on the basis of sex by enacting this policy.
What they SHOULD be doing is raising driver pay and enacting real protections for their passengers which do NOT violate federal law.