As I was corrected and also the OP cited article, Chlorine dioxide only turns into Chlorine upon sun exposure.

when exposed to sunlight there is a chance that chlorine can be produced

Anyway I don't trust any stuff that turns into something even more poisonous upon sun exposure.

Take for example mushrooms exposed to the sun they produce D2 vitamin.

So to any health panacea: Be like mushrooms... turn better in the sun!