Nor is it so clear that traditional (circa 1980-2006) American conservativism is particularly more self-consistent -- why, for instance, does it tolerate government intervention in the bedroom, if it considers it so imperative that government stay out of the boardroom?
In the comments thread, someone points out that progressives simply reverse the paradigm: bedrooms should be free while boardrooms should be regulated. Thus if Silver really values freedom in both settings, his position is much more libertarian than progressive.
The implication here is that progressives are no more concerned with freedoms than are conservatives, but I don't think this is quite right. The problem is in the rhetoric, not the superstructure. Conservatives define government intervention as bad, and rally against government regulation of business, multi-lateral diplomacy (where presumably negotiations interfere with the will of the American people), and even a federal presence in the healthcare industry. This last reveals the rhetorical rather than structural nature of the position when we find multiple people at right-wing rallies carrying signs that say things like "Keep your government off my Medicare." But this rhetoric fizzles when it comes to the bedroom or the body.
Progressives, on the other hand, organize their rhetoric around...progress. It's not good (enough) how it is now, so let's fix it. The driving force behind this rhetorical stance is that of humanism: through the application of reason and communication humans can improve the situation of all members of society. Because humanism's aim is inclusive of all humans, it looks for betterment for all those considered human. This means staying most of the way out of the bedroom (drawing the line at consent rather than normativity), but it also means staying in the boardroom, if for no other reason than to observe (with the possibility of intervention) those who wield power over the disenfranchised.
Progressives will use the language of liberty and freedom, but in the service of human progress, not as a point unto itself. The ideal of humanism is a state in which we are all free, but a responsible humanist is not so naive as to believe that absolute freedom now will beget absolute freedom tomorrow. As such progressives (think Jimmy Carter here) are more likely to talk about sacrifice and hard work and helping hands, while conservatives will talk about self-reliance while they release the dogs on the poor.