Who can say "No" to China?

I'm interested in this article, but haven't posted since I found it. The reason? Well, I was going to comment on the article, but did have few time to elaborate. Anyway, it's written by two renowned economists, Alan Auerbach and Maurice Obstfeld. The summary is:

As the debate over China's exchange-rate policy and the US response intensifies, this column argues that a large Chinese revaluation – whether forced of voluntary – will not be a free lunch for the US. Drawing on a theoretical cost-benefit analysis, it suggests that if the US wants to create jobs at the lowest costs, it should first consider further fiscal expansion.

I'm not 100% sure, but I can't wholly agree with the conclusion. What if the US doesn't require Chinese revaluation anymore? Complaints on China's currency policy are coming from not only advanced nations but also emerging countries like India, Brazil or Thailand, which is cornered to think seriously of restraining foreign flows to the country. If the US doesn't say anything, who says? Who else can say "No" to China when China has amassed huge political and economic clout over the globe? I think that currency matter is, like the other economic policy, highly political in the sense that it shouldn't be viewed only from an point of economics.