Perhaps a pseudoanonymous currency's value is correlated with the oppressiveness of the local govt? I can imagine circumstances where someone might be willing to pay a premium for BTC solely based on their desire for the privacy of their transactions.
But even if they are willing to pay a premium, at a $100 spread there should be a lot of traders willing to jump into the market which would close the gap, unless they are prevented from doing so. If there are capital controls they are surely on USD not BTC, so if anything USD should be more valuable within China.
Spreads for fungible commodities are generally not good. They mean that either a) somebody is getting massively screwed by paying a price that's way off the mark, or b) nobody's actually trading, which means the asset is illiquid. That is, unless there is some real reason why a BTC should be worth double in China what it is in the US.