I don't believe that having sexist attitudes is a binary thing (you're welcome to disagree).
People have a range of opinions that could be described as 'raging Misogyny' at one end and ,I don't know, maybe 'extreme radical feminism' at the other. And everything in between.
The reason gender identity bs has taken the place of sex in life and society in the way it has is that for most people, it's gone under the radar.
If I can alert some blokes I know to the depths of the nuttery that is going on so that they can begin to challenge it in their sphere of influence, then I will do so.
I agree, a 'raging misogynist' is unlikely to campaign for women's rights. But there are plenty of blokes out there who are husbands and partners of my friends who are, I'm sad to say, mild to moderately sexist without even realising it. These guys would be aghast at men in women's sports and changing rooms and vocal about that.
So I'm not going to ignore their support on gender issues just because they don't pass your 'purity of thinking' test. That's really politically naive.
And who knows, finding out more about gender and its impact on the women they love may soften their views in other ways (unlikely but I live in hope).
You speak as though everyone in the world is either totally sexist or fully feminist and in my experience that's just not true. People are complicated and so are their attitudes.