I don't think one should regard KI as such. The reaction as described should be mainly H3O(+), K(+), Cl(-), and I(-). That is why I questioned a chloride should be the major product.
Re: Deiodination reaction
Since I(-) can react with an aryl iodide to give an aryl-H + I2, then a similar reaction in this case would give pentane. Again, not a chloropentane. However, that would imply alkyl iodides react with iodide to give an alkane. Now think of all the reactions to give an iodide. If iodide reaction was that facile, they would all give alkanes instead. This doesn't seem likely.
Given the nature of the question, I'm guessing the product is a mixture of chlorides and iodides. The Finkelstein gives an iodide because NaCl precipitates from acetone driving the reaction forward. In this case, I'm guessing a product mixture similar to the the ratio of [Cl]/[ I]. Also, because this reaction is in water, I'm not excluding alcohol formation.
If this wasn't a test question, I'd ask someone to look up the reaction and tell us what actually happened. The poster could ask his or her professor, but I'm guessing the professor doesn't actually know either (besides refusing to answer). Practically speaking, this seems a dumb reaction to try, in my opinion.