When I was a PhD student in the US (EU citizen) it was impossible for me to get any employment. The immigration rules in the US are so hostile towards anybody wanting to stay based on the argument that you can provide value from your contribution it's ridiculous.
The rules regarding technology export control are even worse (http://en.wikipedia.org/wiki/ITAR) - if you are not a "US person" any other individual is not even allowed to talk to you about many types of technology work, no matter where you are physically located (at the threat of severe punishment). While export control is not an issue in academic settings, in my industry (aerospace) it closes doors faster and harder than even the US' immigration policies do.
The US treats immigrants (legal or not, educated or not) with such disdain, why does it surprise anyone that people who have a choice no longer select to stay here? I applaud China's government for acknowledging the value of educated individuals - if the US government/culture were to value education even a fraction as much it would solve a lot of problems in this country (poverty, teacher shortage, etc.).
What is really scary about this IMO is not the potential for spying, but the potential for control. You know the tech will evolve, from controlling bugs, to controlling common pets, then primates, then humans? Forget spying, think of the potential of remote controlling people - granted it sounds like a long way to go, but you know its going there. Even though it's "just a bug", controlling other living things does not seem right
"Remember, extremism in the nondefense of moderation is not a virtue." -- Peter Neumann, about usenet