It doesn't mean much.

This reference is in conflict with the vast majority of studies which have shown that iodine-based water purification tablets reliably kill giardia, and that chlorine dioxide takes care of both giardia and beaver fever.

If chlorine dioxide didn't work, everyone who uses municipal water that includes treated and recycled water would be dead, and bleach wouldn't work in the manner that it does. Ditto iodine as biocide for medical work.

Remember, it was once "proven" that bees couldn't fly.