While Barbara comes at it from a different angle, she reaches a similar conclusion to the conclusion I reached in my post: "Do social norms trump the law? | My response to the "Free The Nipple" controversy".
But I think she misses the strategic significance of this particular issue. While she identified that it's not the social norm for guys or girls to be topless in public, at the same time the deeper issue which I identified is that obscenity itself is what the social norm is about. According to the community definition, it is considered "obscene" for women to be topless and this much is clear, but is it obscene for men to be topless? It is possible the community could decide it's only obscene for women to be topless and that a social norm could put more of a burden on women than on men.
And why is this? Social norms being community defined, they are not always rational. It's actually just about accommodating to and acquiescing to the feelings of a collective group of people who enforce the social norm often through law, but also through coordinated shunning and extra judicial means when law doesn't go far enough.
It is by this reasoning that I reached my conclusion that social norms trump the power of the law.