Firstly, that's not exactly how a lease to buyout works. If only it were that simple. Adjusted Gross Capital Cost, No, you won't end up getting $6,500 off the car. Once you go study how the lease works and the Residual Value (around 54% of the retail price), Depreciation Amount, Rent Charge (Residual Value + Adjusted Capital Cost x Money Factor), and get all the numbers in place, you'll quickly learn it ins't like you are getting $6,500 off the price of the car PLUS the amount you negotiated down.
And no, this is not unethical to do this. Kia Financial offers these programs legally, and lays out the terms and how they work. It is up to you if you how you choose to utilize their program. This is much like a Credit Card company offering $500 if you spend $6k on their card in the first 3 months. You can do that and cancel the card. Again, nothing wrong with this. But the Credit Card companies, like lease deals with financial companies, know about 2% of everyone actually use their programs in this fashion. Rather, people carry balances, pay lots of interested, pay the annual card fee, etc...
They all know the % of people using the program for customer benefit, and their numbers are all baked to take in those folks. Perfectly ethical, thus perfectly moral.
Good luck!