Chlorine dioxide is used in water purification and a lot of other disinfecting situations. Chlorine dioxide is generated by adding an acid to sodium chlorite, then bubbling air through the mixture to strip the chlorine dioxide out of it. It is collected in a separate container of water, then diluted to the concentrations needed for water purification (usually less than 5 PPM). When chlorine dioxide is added to water it does not change the PH of the water.
In contrast, Miracle-Mineral-Supplement involves adding an acid to sodium chlorite, then using it. What is generated is chlorous acid in concentrations much higher than 5 PPM.
The 4 part presentation is correct for the proper use of chlorine dioxide, but does not apply to Miracle-Mineral-Supplement because it involves a different process.
Acidified sodium chlorite solutions are not approved for water purification because they end up with higher chlorite levels than what are allowed. Acidified sodium chlorite solutions are used to stabilize the bacterial growth on food between harvest and consumption.