Adding minerals to the sparging water is probably best for several reasons. Increasing the osmotic stress on the cells and membranes from the grist should help reduce the extraction of tannins and humic acids. Any Ca or Mg added to the sparging water will react with any remaining phytins in the mash and continue to produce their pH lowering effect. Any oxalates that are extracted late from the grist may be more likely to complex with the Ca in the sparging water and precipitate out of the wort.
I assume that Dan is referring to the buffering offered by adding alkalinity to water? Since we shouldn't be adding alkalinity to sparging water, he is correct that you would not add minerals such as baking soda, lime, or chalk to the sparging water. The other typical minerals such as gypsum, table salt, and calcium chloride would not increase mash pH.