You need to prove that China's totalitarian policies are A) responsible for the growth and that B) all the deaths and lack of freedom attributable were somehow justifiable (they aren't). A big problem for your argument is that Hong Kong is a bigger, brighter, and longer burning success story than mainland China. Hong Kong avoided the totalitarian nastiness that the CCP's government currently employs (great firewall of china, no free press, no freedom of travel, etc.). In some ways China today is worse than in the days of Mao since the government has the technological means to monitor everyone's communications and travel at a very large scale.
I said that Hong Kong avoided totalitarianism and is an much larger success story than mainland China (both of which are objectively true). I never claimed that democracy is responsible for Hong Kong's success.