Also, those arguing that governmental assertions of free speech rights only apply to government actions are not familiar with the relevant case law in the US. [2]
Similarly, those claiming that censorship can only be done by state actors are using an incredibly idiosyncratic definition that basically anyone other than a hardcore libertarian would disagree with. [3][4][5] Say it is the 1980s and a college newspaper prints something that upsets someone. They then steal and destroy all copies of that issue once they are printed. How is this action by a non-state actor different enough to be put in another category?
Scott Alexander also has a good read on these issues. [6]
[1] http://www.wired.com/2013/04/aaron-swartz-interview/
[2] https://en.wikipedia.org/wiki/Pruneyard_Shopping_Center_v._R...
[3] https://en.wikipedia.org/wiki/Censorship
[4] https://www.aclu.org/what-censorship
[5] http://rationalwiki.org/wiki/Censorship
[6] http://slatestarcodex.com/2015/07/22/freedom-on-the-centrali...