The CPC has also been adamant that waiting decades for reunification is vastly preferable to using violence for the purpose.

Plus the US and friends are the only ones genocidal enough to be "glassing" countries. Saying China would glass Japan is one thing, but how can you say with a straight face that they would do that to South Korea when socialist reunification is essentially the most foundational element of the DPRK, that close ally of China that shares a land border with it? The DPRK might literally fire nukes on Beijing if that happened.