Earlier quoted context omitted.
> Requiring user testing for shades of blue and thicknesses of border is the height of silliness. No it isn't, if a designers ideas cannot withstand a little objective scientific testing, they aren't worth using. > Moreover, users often don't know they want something until a designer shows them they do. You can never get to those designs by testing blues and borders. Which is the whole point of objective testing, do…
From the way I understood it, he was suggesting that testing for shades of blue and border thickness is nitpicking. An equivalent nitpick more familiar to us would be testing whether using tabs or spaces for code indenting improves coding efficiency.
If it affects conversion, then it's not nitpicking, tabs vs spaces isn't a valid comparison because it can't be so easily measured.