How about innocently asking "how would that help?"
In the case of quota, they are necessary because of women not being promoted to higher positions as frequently as men. This has nothing to do with your gender in your ID card.
In the case of pay gap, most of it is explained by jobs most often held by women being payed worse. This doesn't get better by changing your gender.
With just asking "how would that help?", you put the other person in a position to explain their argument, and maybe they reflect a little.