Apparently, probiotics are already fragile. Most probiotic supplements have special requirements for ingestion. Some have special coatings to protect them from stomach digestive fluids. Some request that they be taken with meals to try to hide them from the digestion. Some request that they be taken with a lot of water.
Externally, CLO2 is used as a disinfection agent. It is well know to destroy anthrax externally. It is used in swimming pools; and to disinfect drinking water. I suspect something else is going on in the colon in contrast to an external medium.