I'd bet a chunk of cash that it's segmenting people, at least initially. And the "gender A" segment are seeing the ads that are popular with the "gender B" segm

I'd bet a chunk of cash that it's segmenting people, at least initially. And the "gender A" segment are seeing the ads that are popular with the "gender B" segment at a far lower rate, or not at all. So it's not an individual's revealed preferences, it's a group's revealed preferences. And that's where the discrimination comes in.