Interesting reading but as I read it the techniques used would be very specific to a limited number of systems (i.e. no generic attack) and blocked by the use of a TPM. The attacker would have to have some pre-existing knowledge of the target (or be very lucky) and the target couldn't be using a TPM. For anyone that would be a target of this kind of sophisticated attack I doubt they would leave a laptop with critical data on it unattended or even that they would be carrying a laptop with this kind of data on it. Anyone targeted this way would probably be as sophisticated as the attacker.
Paranoia abounds, but in real life it's rarely justified. In the context of the original question - we don't have enough data. If bitlocker or some other form of disk encryption wasn't in use and the OP is worried the solution is to wipe the hard drive and restore from a backup taken before travelling to China.