Not true for this DX I have here. The charging cable is a USB cable, and the Kindle becomes just another mass storage device (acts like a thumb-drive) when I plug it in. My model does not have WiFi, and sometimes I've stayed at hotels in areas without 3G. I downloaded files from the Amazon website directly into the Kindle via USB cable.
It is possible to connect a Kindle directly thru a computer and I know you can charge thru the computer with a USB cable, but with the equipment Signalman had at his disposal, he didn’t need to. Windows seven networking in one computer can be a bit wonky about letting devices, other than other computers share a computer’s internet connection via USB so I was trying to make it simpler for him.
It’s true the Kindle can act as a storage device, ie; you download to the computer first then move the file over to the Kindle’s memory..... that is, if he was in some remote hotel somewhere with only a wired ethernet and no hotel wireless(and no 3g). Yet 99 % where will signalman be? He’ll be near a wireless router or in a 3g area. He won’t always be in a remote area with access to a wired computer.