This guy talks about how much he loves free speech but anytime a free speech issue comes up, he errs on the side of censorship (when the speech is not "obviously good").
From what I've seen, he actually cares less about freedom of expression than the average progressive.
Now, different people might draw different lines, but it's hard for me to call someone who only has an interest in defending speech he personally supports the "fiercest defender of free speech".
It's not simply this example. There have been quite a few examples of this.