[rayiner]

Characterizing it as a "favor" isn't helpful. It's more appropriate to say that there is more to the calculus than just the actual loan. Holding US debt has a direct benefit to China, but also an indirect benefit (it allows the U.S. to keep running huge trade deficits, which benefits Chinese manufacturing). If you look at just the return and risk on the debt, China's actions might not make sense, but if you look at the whole picture they do. At least, that's what the article is trying to get at.