These are xy points on a standard graph that presents color performance in a 2-dimensional space. Neutral gray, which is sometimes referred to as D65, has a very specific definition of 0.3127, 0.329. A better measurement is Delta-E (dE or ΔE), which is a mathematical measurement of the degree to which a color deviates from an established reference.
In such a case, the image would look awful. Measuring grayscale in Kelvin ignores green, so a display could have an appropriate balance of red and blue and thus measure near 6505K, but suffer from a severe excess or deficiency of green. This is fairly easy to understand, but it is also a little misleading. Results lower than 6505K mean that the display's color temperature suffers from excessive red, while results above 6505K mean that the display's color temperature suffers from excessive blue. This roughly corresponds to about 0.6%-100% of the display's available light output. Gray scale is commonly measured as a +- color temperature deviation from 6505 degrees kelvin across a specified range of output, which is usually presented in % video, say 10-100%. This is the measurement you see most often cited in reviews. The color performance of any display is measured in three ways: the grayscale, the gamut, and the luminance of the colors. Color performance is not well understood by the general public, and even magazines aimed at home theater enthusiasts often get it wrong.