Liu's broker at LME shouldn't let him establish such a huge short position, without checking wether he can deliver or not. But it happened, Liu made a bet and the brit in Lodon helped.
Put it in another way, if I were to shorted x amount shares of google stock, and my brokerage house executed the trade on behalf of me. Google has a sudden runup, and I got a margin call. But I don't have enuf cash to meet the call. The question is:
Should my brokage house take the loss or should my brokage house ask China to take the loss because the trade was made by a Chinese?