titration of ascorbic acid

In this article. Authors use $\ce{KI}$ in potentiometric titration of ascorbic acid with permanganate and dont describe why! Anyvody know why should we use $\ce{KI}$ in potentiometric titration of ascorbic acid with permanganate?

Potassium iodide is used as an indicator. While there is ascorbic acid in solution, $\ce{KI}$ is protected from being oxidized by potassium permanganate. However, the moment ascorbic acid runs out, potassium iodide gets oxidized to iodine, $\ce{I2}$. This gives the solution a brownish color (blue if you add starch, which will also make it easier to see).