Livre d'Or

I think that people's ideas should be judged on their merits - people ought to be listened to if what they're saying is (objectively?) useful and interesting, not on the basis of their gender.

Yep, exactly. They're not saying "we should be listened to because we're male", they're saying "we should be listened to because we're smart and well-informed" — but smart and well-informed people are often ignored because they're not male (or they dress "wrong" or have the "wrong" accent). The fact that these people find it surprising that they're not being listened to is a sign that they have a certain amount of privilege; and given that they seem so well-informed, they really should be aware of this.