Are you simple, dishonest or both? The >14-stop-DR fallacy has been discussed multiple times, and has been quite convincingly proven to be just that, a fallacy. You get better SNR from downsampling, but DR cannot magically expand outside the source data boundaries. Get a clue already, please.
Insulting the original poster while being wrong yourself is not particularly smart.
Of course you can achieve more than the per-pixel DR by downsampling. Suppose two cameras have identical idealised pixel-level DR, but one has double the resolution. With even lighting, the light-per-area is the same on each sensor, but one sensor has double the number of pixels and hence double the headroom. Of course, the higher resolution sensor has more shadow noise, but down-sampling reduces the noise and hence the result is greater DR - more than can be achieved by a single pixel.
In the real world, the light is probably not equally distributed between adjacent pixels, meaning that one may clip before the other (you want something useful from the resolution increase, after-all), and things like system noise also complicate things. However, none of this prevents a down-sampled image having more per-pixel DR than the original sensor pixels, particularly when the downsampling factor is large (4.5x for the D800).
The DXOMark tests are lab-tests, and probably use uniform images for DR (which will tend to maximise the DR benefit from downsampling a D800) and use a lower-noise floor limit that may or may properly account from the pattern noise on many Canon sensors. The DXOMark tests appear to be well performed and accurate - though you need to understand what they are measuring.
If you still do not accept that it is possible to increase DR by down-sampling, I would take a look at the many applications in which oversampling is used to improve performance. A good example is the 1-bit DAC in some CD players. The DAC is produces a single-bit signal that is hugely oversampled (in the time domain). This is then down-sampled by a filter, yielding a result equivalent to a 16 bit linear DAC (or more).
So not only is it possible to increase DR beyond the native capture range, it is a widely used technique in signal processing.
Of course, the real problem here is that people only want the numbers to show that their purchase is somehow the best and opinion is as valid as understanding. I have seen similar discussions at school in the 1980's - my home computer is better than yours. It is all a bit depressing really.