There are several discussions about vitamin C and each time Jim Humble says about the same thing. He says that vitamin C is a preservative and preserves the sodium chlorite so that the ClO2 can't be released.
I too was shocked at this, but he seems to have forgotten how vitamin C works.
Remember, he says that he has done lots of tests with vitamin C, but he did not realize that you could activate sodium chlorite with it. While I agree that the resulting solution is weaker, it is still strong enough for use. It actually works out to be 1/3 to 1/2 the strength of a solution activated with 10% citric acid .
I think Jim needs to run a few more tests on vitamin C and get a better understanding on how it works.