Maybe I'm missing something but if "he doesn't have internet and probably never will get it", what use can he get from the Kindle? You want him to use it freely without depending on you, but if he can't access Amazon or other sources how will that happen?
I assume that you got him the DX because of the larger size. There are lots of Kindle books at our local library and I assume that his will also have a selection.
FWIW I also wanted a DX but the price difference between the regular Kindle and the DX was just too much for me. It's a nice unit IMO.