The cited xkcd also does not do a good job of addressing freedom of speech. Many writers have used "free of speech" to refer to a broad social and cultural principle, not merely a legal doctrine, and defended it on grounds that apply just as much against private censorship and social ostracism as much as against government censorship. The idea that free speech is a concept that is applicable only to government restrictions is of fairly recent vintage, and historically was most used by libertarians rather than the progressives who more often promote it now. In summary, John Stuart Mill had much clearer and sounder ideas about free speech than Randall Munroe.