Sell the binary on CD, then put up a website behind a dialup, run off a Palm Pilot with Apache on it. Tell people they can dowload the 2 gigs of source there. Seems reasonable that the source should be at least as accessible as the binary, and in the same manner.
I wonder if anyone actually tried this, or if the clause is anticipating a hypothetical? Imagine the brainstorming sessions to figure out ways to cheat the GPL.