[ehnto]

You're correct but I think you are addressing a different problem. He was mentioning the issue specifically about differences in tension from turning the peg clockwise versus counter clockwise.

If you tune downard tonaly, so from an F# and you want an F, the string will more easily fall out of tune. I am not sure what causes this, some interplay between the friction of the peg and the final resting position of the string on the nut being different depending on the direction maybe. By tuning down perhaps you end up relying on some of the friction from the nut which goes away quickly as the string settles to an equal tension on either side of the nut.

I have noticed it's not as much of an issue on carbon nuts or well made nylon/bone nuts.