I don't think that matters, as long as rules are applied and enforced consistently. Outside the enthusiast overclocking community though, records like this are irrelevant and, have no bearing on potential performance in normal use.
What good are memory overclocking results if you have to cripple the CPU beyond usefulness to achieve sufficiently low noise and non-memory power to make it work? If you throw away meaningful usability for the sake of pushing GHz no matter what, may as well allow people to use DRAM development boards with semi-custom ASICs and FPGAs too.
If we're going to be testing memory, then do everything else as optimal as possible, if that's cherry-picking a CPU with an insane IMC and disabling some cores, so what? We're testing memory, not CPU. If we were testing CPU cores, then sure, but if we're testing memory?
Also, to take the 20 000 RPM example, why don't we just put a 20000LBS load behind the car and see axles and engine parts fly. The parallel is that the IMC works, but if you lessen the load in other areas, can be pushed even further, same as if we remove that 20kLBS load from behind the car. It won't break (lockup/crash/etc).
And why? Because we're not testing the CPU or IMC, we're testing how well the MEMORY holds up. This is a memory world record, not a CPU or IMC world record.
If AMD had a stronger IMC, then would it be cheating using that? No? Why not?