Sounds to me like they're saying NVidia don't want their board partners binning the chips, so that lower end cards potentially overclock as good as higher end cards, depending on temperature. And they don't want them to factory overclock the GPUs, GPU boost 3.0 will do this anyway. I have no reason to doubt any content on the Linus tech tips channel, so it's probably true.
Whenever you buy a new GPU, it's a lottery (unless it's been binned) as to just how well it will overclock, sounds to me like NVidia want to even the field a bit by preventing the cheaper cards getting the worse GPUs.