While I didn't read the article, I wonder if he was misquoted and meant hyperthermia vice hypothermia.
Bill
My first though was much the same. It is pretty common in deserts for the surface temperatures to be well above 100F. Dig down in even dry sand and it can be 30F cooler. Standard desert strategy for hyperthermia, too high a temperature.
Then again if you could find dry sand digging in would, at the very least, get you out of the wind and might slow evaporative cooling so it might work for hypothermia, too low a temperature, also.