I am failing to see a legal risk. Even if you do the self-test (and test negative), there is always a good chance to catch covid while being on your way to China (or you catched it just prior to the test, so it wouldn't show yet) - how would they make a difference between "tested negative, but later been positive when arriving" and "didn't test, just declared negative and tested positive when arriving"

Basically, Covid is over, and what's currently done is "for show".