Oxidants and antioxidants cancel each other out. The goal is to have the body in balance. Vitamin C is only one of may antioxidants that neutralize oxidants.
If you have an abundance of weak or dying blood cells that are infected, killing them through oxidation should be helpful. Unfortunately there have been very little investigation along these lines.
Sodium chlorite as an oxidizer does not oxygenate anything. It kills through oxidation. The reason the oxygen levels increase is that you have new cells that are more efficient at delivering the oxygen you breathe. However, gasses like chlorine dioxide actually displace oxygen in the blood cells causing a drop in oxygen levels if the concentrations are high.
Once again the goal is to have the body in balance.