Why Let China Continue its One Child Policy?

A person or nation should never look a gift horse in the mouth. China's one child policy may be abhorrent to Western sensibilities but it is a policy that is actually beneficial to the U.S.
China's one child policy is actually working in the favour of the U.S. because this policy is leading to China facing a demographic implosion just when it is on the cusp of being the biggest economy in the world. Given this fact it seems that China's place at the top will be short lived compared to that of the U.S.
China's one child policy also has the country facing reproductive capability problems due to the fact that its gender ratio is skewed towards males. For a country to have too many males is a recipe for population decline.
China's one child policy means that China's army will face problems when it comes to fighting members. The lack of sufficient young people will also pose a problem to the productive capacity of the Chinese economy. Young people who are forced into the military are young people who will not be available to produce material goods for export or domestic consumption. These are young people who will not be using the intellectual capacities for designing consumer or industrial goods. It is also the young who engage in the production and accumulation of wealth.
How China will confront these looming problems is yet to be seen. However it is safe to say that any attempt to confront them all will mean that none of them will be dealt with well. If China were to attempt to pursue the goal of maintaining or acheiving military parity or superiority with the U.S. then it will have to neglect economic growth and the establishment of a social safety net that would care for the old. Whilst the pursuit of economic growth will allow China to confront the needs of an aging population but will mean it having to direct less resources to the military.
I conclude therefore that although the one child policy is morally repugnant that it actually is a policy that in the long run actually favours the U.S.