This stirs up all sorts of questions about location and the prevailing standards in the jurisdiction you're in. Does the set of hashes used to scan change if you cross an international border? Is the set locked to whichever country you activate the phone in? This could be a travel nightmare.
If the situation OP suggests happens in the form of FBI/other orgs submitting arguably non-CSAM content, then Apple wouldn't be complicit or any wiser to such an occurrence unless it was after-the-fact. If it happens in a way where Apple decides to do this on their own dime without affecting other ESPs, I imagine they wouldn't upset CCP by applying US guidance to Chinese citizens' phones.
I am no expert of what it means to the US, but I’d assume there can be a lot of definition of what “child”, “abuse” and “material” mean depending on beliefs.