re: Speculation
I'm way out of my depth here, but doesn't this assume that the computer responds instantly to requests?
Couldn't a clever computer operator rig his browser to throw "delays" into its interaction with the internet, so requests from his computer might be held for a fraction of a second longer than normal? And couldn't those delays be programmed to randomly change?
The way I see it, trying to do "GPS" this way would be like trying to do regular GPS if the speed of light varied radically and randomly with time.