Whatever WeChat's links with policing in China, I believe that they have an equivalent of Face ID to authenticate users. Keeping in mind that WeChat is used as

Whatever WeChat's links with policing in China, I believe that they have an equivalent of Face ID to authenticate users. Keeping in mind that WeChat is used as an electronic wallet and almost bank account in China. It would have been better journalism to mention this instead of only going for the angle of state policing. It's likely that WeChat already had the person's biometrics details because of the above. Of course that's less catchy than implying that they requested biometrics details because he had posted about Tiananmen commemorations. (though the end result is likely the same)