Xi Jinping wants to coax Taiwan into “national reunification.” The Chinese president gave a speech Wednesday touting “one country, two systems”—the Hong Kong model—as a basis for cross-strait relations. In 2017 Mr. Xi claimed Hong Kong enjoys “more extensive democratic rights and freedoms than at any other time in its history.” The argument was strained even then, and civil liberties only regressed in 2018.

Start with the imbroglio over the Hong Kong National Party, outlawed in September after it advocated for Hong Kong independence....