The question is, where does the junket - or the casino, since they work together - get the USD when its only income from this activity is the debts it collects in CNY.
That's a side of the story that isn't explained here. However it's not a mystery who would want to be on the other side of that transaction. After all, an enormous part of the Chinese economy is international businesses who sell Chinese goods for dollars but need to pay their Chinese suppliers or workers in renmimbi.
Exactly this. It seems likely this is a giant money laundering and exfiltration scheme that both the US and China would nominally like to stop. That they don't is problematic.
It's not that easy. Every step of it has a legitimate use and it's only when combined that problems are caused. Then, I don't see what reason the US would have to want it to stop, more USD in Chinese hands isn't a bad thing. China wouldn't like it, but as it's taking place in Macau or now Saipan there are jurisdictional issues.
That's a side of the story that isn't explained here. However it's not a mystery who would want to be on the other side of that transaction. After all, an enormous part of the Chinese economy is international businesses who sell Chinese goods for dollars but need to pay their Chinese suppliers or workers in renmimbi.