Probably nothing. There would maybe be a few blog posts about it. Their comments would be filled with men defending his actions and suggesting that anyone calling him out was lying, that the real problem is "women that get offended too easily" or "women that don't get jokes," and straight-up male superiority.

Pretty much. I for one have had it up to here though. The next incidence I encounter will be called out at the very least to the person's face on the spot, if not also online.

I don't know how it works in the US, but it's her face and her name, so can't she just get a lawyer to get a court to order the website to hand over some details? And then get another court to get the ISP to hand over some more details? And then give those to the police?