Firstly, the C919 is full of western sub-systems. Companies form the West gain the most with little benefits left for Chinese aerospace suppliers. The US can also drag its feet on giving the C919 certifications, ensuring the project is a money sink for Chinese aerospace industries. Either way, the US has already ensured little money flow into key Chinese aerospace industries. Secondly, as of now the C919 is still purely a civilian project. The US can restrict suppliers from delivering any sub-system at any sign of military involvement. Certifications would be rendered meaningless without those western sub-system, while new certifications would not be given out to the aircraft with Chinese sub-systems. When that happens, no one would want the aircraft, and so Chinese aerospace industries still wouldn't get any money. With the life or death of the C919 in US's hands, of course the US would have no problem approving cooperation.
It doesn't work that way. An example is shown in
. China exports aerospace vibration test platforms capable of testing anything up to 50 tons in weight. Yet, the US still embargoes China on platforms that can handle more than 9 tons.
The thing you have to realize is that it isn't about making or losing money. It is about maintaining technological superiority by pinning down China's aerospace technologies, because that technological superiority is related directly to military superiority.
Interesting and well thought out ideas, but I think you are being a little too pessimistic. For one thing, I doubt the various American agencies and companies involved are anywhere as unified in purpose or coordinated to do what you suggest.
The C919 having lots of western subsystems also means western companies have a vested invest in seeing it pass certification.
But in any case, the C919 is more like a by-in, in that China does not expect it to instantly catch up with Airbus and Boeing, it is more of a learning experience and investment for future models by setting up a commercial airline maker, gaining experience and getting a handle of western markets. But even then, western market penetration is very much a distant secondary consideration. The main prize is China's own massive and rapidly growing domestic market.
American and European markets are already mature and saturated with very limited growth potential. That means the bulk of future growth and sales will come from emerging markets, and China's is far and away the biggest. China is investing in airliners because it knows it has huge demand for them, with that demand only going to increase in the future. Right now, all that money is going abroad, but if China has a domestic airliner, even a tiny fraction of the domestic pie would be enough to keep the new company going and give them enough profits to invest in new designs. Once Chinese airliners get good enough, Chinese airlines will buy them because it makes business sense to do so rather than because they were told to. That means bigger sales which in turn should further strengthen the new indigenous airline industry, and you get a snowball, effect going. That is the main goal, but that is at least several generation of airliners and a couple decades down the road from now.
Right now, the C919 is just meant to allow China to get into the game. There isn't, or shouldn't be any great expectation of it taking ! Europe and America by storm. All it needs to do is give solid but unremarkable performance and above all else, not suffer any serious accidents so they can build the brand name and earn the confidence off operators and travellers so there would be no problems with airlines ordering whatever airline China develops next.
America can play games with the C919 certification if they want, but that would be an incredibly stupid and short-sighted thing to do, since China can also play games with its own certification of future Boeing planes or even go as far as to have an unofficial policy favouring Airbus products.
Even a hint of that would have Boeing working hard to make sure the C919 don't get hit by anything that might make the Chinese think the Americans are playing dirty tricks since the Chinese will just take it out on Boeing if that was the case.
China has long mastered now to use western companies' greed to get them to help China achieve its long term goals, and I do not see why it would be different here.
