It's a fair question.
I think in general i think it is something that companies do need to be very wary of in this part of the world, and ultimately the speed of technological knowledge is snowballing in this part of the world. However i think the Sigma guys have got a massive head start and thus would be more useful inside the tent in order to help set up an asian aerospace industry if something like that would occur. Also, and i think this is important, the aerospace industry globally is both heavily regulated and thus it is harder to cut corners with people's safety. When Comac get's up and running, as it will, it will be an enormous pride to China to compete with the likes of Boeing and Airbus. HUGE. Don't underestimate the milestone this would be to China's development into the global economy. As such any failure or problem would be 'unthinkable'. China is all about face. My impression is that China will spend heavily to make sure the vital parts are under its wing. It's the periphary technology that needs worry more about more local versions. As far as i am concerned Sigma fits into this important proprietary technology and it is something China would love to get it's hands on and be happy to pay for that opportunity.
All this is conjecture at moment, but in many ways this development could make a lot of sense, it does to me.
On top of this, let's not forget Sigma's immediate customer base is in a more patent friendly society. Deals with GE, Boeing, Northrop, Honeywell would see us all in retirement as it is :)