It is the free chlorine produced by both chlorine dioxide tablets or solutions and sodium hypochlorite bleach that is the active microbiological agent in these compounds. It is the free (and dissolved) chlorine gas that produces the "chlorine" taste and smell. Chloramines are produced by the reaction between free chlorine and amino acids.

For most clear lakes and streams, the amount of biological mass suspended in the water is small - on the level of nanograms per liter. In some of the soupier water the biological mass is in the milligrams per liter (ppm) range; it can reach levels of a gram or so per liter. The amount of potential chloramines produced by free chlorine contact with proteins should be pretty small. Most water borne organisms consist of around 10% protein on a dry weight basis and for most of these organisms the dry weight:wet weight ratio is about 0.3 or less. Proteins are composed of amino acids.

I wouldn't just treat cloudy water with ClO2, it would take too much to be sure all the bugs were dead. I filter water that is cloudy or that I can't see through before I treat it with chlorine dioxide. But, if the water is clear I just add the pill and wait. One reason that I often filter and then chemically treat is that a lot of the water I find in the desert mountains is pretty cloudy and after filtering it still can have a rather foul odor and taste. The ClO2 tabs remove much of the icky aroma.