Why would they stay? China is seeing a huge boom in the tech industry and it's only the beginning. The future is there, not in SV. I'm kinda jealous of my friends who learned Chinese in college and are now working there.
I think that's a little unfair to characterize the Chinese government as uniquely nefarious. NSA's Prism gives the US Gov't free reign over troves of information held by US based software and information services companies.