Looks like Whitney was recently measured at 14,505 moving it ahead of Volcan La Malinche on this list.
You bring up a very interesting point. I have spent time considering changing the display ranking and elevation of Whitney on the list.
I decided against it after consulting my friend Greg who owns and maintains the site Peakbagger. This is what he had to say on the matter, "Given the various vertical datums in use around the world, surveying inconsistencies, difficulty in determining sea level under mountains, and other factors, I would say that most elevations are truly only accurate to about 10 feet or so".
Further discussion among some mountaineers I know seemed to suggest that at the moment we are operating on an old system of measurement. The height of Malinche is also likely to have an error range. Until this new technology makes widespread reforms and all peak elevations are officially adjusted accordingly, it seems apt to stick with the widely known numbers to avoid confusion.