As the GP points out, the fact that buying sex remains criminalized means that this is, indeed, a sex-negative approach.

I’m elaborating on his explanation that “bodily autonomy” (i.e. social libertarianism) isn’t the point of the bill. Lots of people—in particular, most women, reject the social libertarian view that prostitution is acceptable: https://www.vox.com/2016/3/11/11203740/prostitution-legal-me.... Many of those people, however, would agree (like Dworkin) that the reason prostitution is wrong is because it is violence against women.

The upshot of that is you can get enough support to pass a law decriminalizing selling of sex (something social libertarians and many sex-negative feminists could agree on), while lacking enough support to decriminalize buying sex (which only social libertarians would support).