Laws involved in everything from cable TV regulation to advertising to union dues have come under 1st Amendment jurisdiction-- the most radical development being the equation of money with speech, thereby making the regulation of money in many cases the same as a free speech violation. In some cases, that makes sense-- I actually generally think the campaign finance decisions by conservatives have the issues right -- but since the Supreme Court has changed the meaning of "free speech" over the years, it's hardly surprising that liberals who defended one version of free speech in the past might not rate as highly under a Rehnquist Court mostly defending the commercial dealings of powerful corprorate interests.
...In the early part of this century, the major constitutional cases defending "liberty" were about striking down Congressional child labor laws and other state regulation. Justices who deferred to government regulation, like Oliver Wendell Holmes Jr., were seen as standing up for individual rights against corporate interests who were using dominance of the courts to break the free speech rights of unions and other groups protesting corporate power.
...The interesting Justice on Volokh's list is Stephen Breyer, who rated as the most anti-speech Justice. This may reflect a more general characteristic of Breyer as one of the judges least favoring judicial activism in most areas, social and economic. I noted his comments in the judicial penalties case where he wanted to defer to state penalty rules, since he thought judicial interference created rigidity in systems better left to democratic debate.
...What the survey also reflects is judicial activism; to the extent that the conservatives are protecting free speech more, they are also being judicial activists, something conservatives often express disdain for. So to the extent that conservatives want to claim free speech bragging rights, they will also have to reliquish their supposed judicial restraint claims.