This is great. He extracts timestamps from the TCP ISNs and uses that to measure skew of the CPU clock and thus the temperature. We can then tell how hard the CPU is working by measuring the temperature increase.
People already know that time is a side channel and that you shouldn't leak information in the speed in which you process queries. Now you have to heat the CPU uniformly too. Giving out such good timestamps via the TCP ISN is probably a bad design and should be stopped. But there are many ways to get a timestamp from modern systems and noise just means that you need more samples.