the Nyquist limit of the audio sampling hardware of a cell phone over instruction rate of a modern CPU is a pretty small fraction.
The "audio" in question is most likely all below 24 kHz, that being the Nyquist limit for the 48 kHz sampling hardware, unless it happens that some phones can actually sample faster, and have microphones that can respond to higher frequencies.
The instruction rate of the CPUs in question is many times that frequency.
It doesn't sound likely.
Using multiple cores turns out to help the attack (by shifting down the signal frequencies).
Say what? Through what mechanism would multiple cores shift down the frequency? And what about parallel instruction streams contributing to noise?
TEMPEST was a details-secret government requirement meant to defeat means of eavesdropping on classified computer data from its electromagnetic emissions. I guess they need to include audio too.
My impression is that the noise comes from the power supply, not the CPU. I can certainly hear it with some computers, and it is related to work on the video card in my experience. I'm astonished that you can actually pull data from that, and in fact I'd like to see independent confirmation before I believe it.
After only 10 years since it independently sent its first astronaut into space
Independently? The Chinese do nothing independently. They fly to space on a glorified Russian Soyuz.
The job of government is to pay for education.
At some point one must question whether they are doing a competent job. Got the money? We are $17 trillion in debt. You mean other people have the money and you'd like to seize their property. Most rational people will object.