While the DPRK would have no means of doing this, the PRC could quite plausibly launch its own jammer constellation if it became enough of an issue.
The most interesting aspect is that an import ban on LEO satellite modems becomes exponentially harder to enforce when you’re the only country that can manufacture them at scale in the first place.
I'm 90% confident that if SpaceX ignored international (and Chinese) law and started broadcasting into China without permission the PRC would be delighted at the excuse to test anti satellite weapons instead of trying to jam them.
Of course, SpaceX wouldn't dare risk the international firestorm of doing so intentionally. But if the service were available in Taiwan, mainland China is only about 100 miles away across the Taiwan Strait.
The connection might be slow and spotty from Fuzhou, but all you'd need is a modem sold out the backdoor of a factory and an account created in Taiwan (perhaps a friend you Alipay for the subscription), and you'd have unfiltered internet in eastern Fujian.
The most interesting aspect is that an import ban on LEO satellite modems becomes exponentially harder to enforce when you’re the only country that can manufacture them at scale in the first place.