That's absolutely evidence of the opposite. If china thought they could use the app's algorithms to promote national unity, they would do that. They have their own exclusive app.

China thinks its effective at wasting time. Children also aren't allowed to play video games monday through friday, and are limited to 1 hour per day otherwise- a law which existed before douyin limits: https://www.bbc.co.uk/news/technology-58384457

The country that is obsessive about its children and their productivity, the country famous for kids competing in chess and abacus and piano... that country is just banning douyin because it's a time waster.