I was reading up on this and believe you have some very good points. I don't fully understand what happens when the solution is acidified and diluted. I need to run down to the chemistry department and have a TA take me through the reaction step by step.
Then again, perhaps it is time to read through the book again...
When I look through the book again, it sure sounds like not all the ClO2 is generated at once and that some of the sodium chlorite is left in solution. This seems to sustain the reaction over the extended time period.
Balboa, I will have to re-think my response to you.