The majority of the land mass of what we call China is culturally and ethnically different than the dominant cultural and ethnic group. "China" is a remnant of the empire's sovereignty and the one China policy is the continuation of Han imperialism over the inner regions of east Asia.

The comment you're responding to is more about PRC actions in those regions. The PRC will commit genocide in Taiwan if they need to do it to stamp out any lingering sentiment of independence, like they are doing in Xinjiang.