You're conflating rationality with propriety. China wanted Meng Hongwei to make it easier to use Interpol to track down Chinese dissidents, directly in conflict

You're conflating rationality with propriety. China wanted Meng Hongwei to make it easier to use Interpol to track down Chinese dissidents, directly in conflict with the Interpol charter; and merely two years later they kidnap, disappear him, and charge him with disloyalty to the Chinese Communist Party. He was supposed to be their stooge pigeon, but was clearly ineffective. Again from their point of view, entirely rational to have him removed because he wasn't doing what was expected. And that's what's so conspicuous, they openly admit China was his master, not Interpol. China, Xi, and the Party are in a sense all one in the same thing. There is nothing more important than loyalty to the one Party, and the concept of one Party rule. And Uighurs are a threat to that, so they're labeled terrorists. If you accept the idea that one party rule is necessary, it's entirely rational to aggressively, perhaps even violently, ban all possible opposition. That's the nature of any autocracy.