This is for prebuilt machines. Seems pretty easy to test. Turn the thing on, put it in sleep mode, then record the power draw from the PC PSU. Monitors are not included.
You'll see the Dieselgate of PCs. It's very efficient and underclocked while being tested, but when a customer registers the product with the website, the driver app installs the normal performance profiles.
As long as it's trying to trigger on idle, I don't see how it would ever cause me a problem. If the CPU load is sufficiently low for cores to park, then let them.
If you want to disable core parking when not idle, that's fine, but it wouldn't even affect the measurements taken by this law.
Idle is pretty well defined. It's when you close the lid of the laptop or hit suspend. The CPU stops running entirely and ram is given some power to persist data.