FirstNo is correct... since your nephew has no dependents, you will not be able to stay at SoG, or qualify for the overflow rates at any of the other Disney resorts. I would keep my eye out for good rates listed at the top of this board, or visit mousesavers.com. They have been know to have discounts on Disney owned rooms up to and sometimes over 40% off. However, if you have your heart set on SoG or the military discount, you are going to have to wait until he can personally accompany you.
Sorry... oh, and if you do call SoG, you will get the same answer you have here... and will have to pay the long distance bill, to boot!