It seems to me that this credit score system--if real--would ultimately be self-defeating, for two reasons. First, among a cynical and rebellious youth population, a low score would become a prestigious thing, proof of your courage and gutsy attitude, a kind of street cred. Second, it would limit economic activity. If you cut off millions of people from car loans on the basis of their questionable postings or online…
Most Chinese youth arent rebellious in any substantial way. They've grown up in an environment that is strongly Confucian, and there isn't really this "be what you want to be, break free, live life, freedom of youth" narrative that we have in most of the developed world. Kids are very very unrebellious and I doubt there would grow a culture of 'showing off' your bad credit score.
On the 2nd point, I'm not sure either. The political element of this is likely to be a small factor, not a prime one. The government tends to be very specific these days about targeting people who are activists rather than cracking down on anyone who says anything. Finally, people in China are generally used to this kind of BS, and whether consciously or through 'brainwashing', they don't tend to randomly spout political positions or anti-government rhetoric unless they know they are on safe ground. I don't mean it won't be an oppressive, inefficient, opaque and abused system, just that it won't result in millions being locked out of loans or the economy suffering that much.