This is true, but only as far as people can keep their Github accounts anonymous. A couple months ago the government tracked down three people who had been using Github to share censored content and arrested them[1]. A whole bunch of other repos shut down quick smart after that for fear of more arrests. We can only hope some people outside the country made local clones.

[1] https://www.hrw.org/news/2020/04/27/china-free-covid-19-acti...