This is most likely a hardware fault and could even be a design fault that's hard to do anything about, and It's probably not a big enough fault to warrent a recall. I mean, seems like a lot of computers (or even gameconsoles, phones etc.) have problems that shouldn't be happening, not just buzzing/coil whine but all kinds of different faults, but these fault are still happening, and they are usually not fixed unless It's something that makes the machine unuseable for a huge amount of users (like the butterfly keyboard on macs).
Hopefully the problem will be better on future production lines of the SL3, but even that might not happen.
But of course it is a shame, and makes what is a pretty exclusive and tempting looking computer, feel kind of cheap.
I still have a small hope that a firmware update or some other fix could make the sound less pronounced. It seems to me that the sound does change or even almost disappears under certain circumstances.