You have to understand the double speak of what they are saying to really understand what they are doing. The consoles automatic shut down that exists now is something intrinsic to the device itself. It's something you are in full control of, that you can modify in the device settings if you want.
What this is, is essentially giving command authority of the device you own to the manufacturer. Microsoft, for reasons only known to them, can order the device to shut down. And STAY shut down.
They are couching this in terms of carbon emissions control, but this power essentially gives Microsoft an exclusive right to shut you out of a 500 dollar device in your living room. A device you now LEASE from them rather then own.