Copyleft as regulation seems to me an easy way to begin thinking of bridging from thinking of private policy to public policy (plus, folks can stop arguing over whether copyleft is a ‘restriction’ or not, and start arguing about whether it is a good and effective regulation). Recent paragraph:
Copyleft is most usefully considered as a prototype for and test of rules that ought be enforced by more effective regulatory mechanisms. Whether you think software provided without source and permissions should be totally banned, not regulated at all, or only regulated for particular uses or in particular fields (e.g., products and services already subject to other safety, disclosure, and pro-competition or consumer protection requirements), it is absurd to think that developer whim and resources in applying and enforcing the GPL regulates and regulates effectively an optimal set of software. It is time to move beyond debate of a hack of state-deputized private censorship as central to software freedom politics and policy, and on to debating directly state vs. market regulation of software (with all the usual arguments about (in)adequacy of market provision and harm/help of state intervention) as in any field of importance, preferably with very strong commons-favoring bias from both sides (e.g., software freedom market-skeptics and state-skeptics ought agree that regulation by private censorship, which serves proprietary interests almost exclusively, be wound down, and that state entities self-regulate by mandating software freedom for everything they acquire and fund).