So you think the zones would be alot smaller than he estimates? Here's a speculative map of what they may look like.
http://pantheon.yale.edu/~ag335/united_states_dzones.jpg
Well, the final horde isn't the only driver of the death zone---the earlier portions of the horde will propagate a good bit further than that 30 miles. The question is, will they be able to swamp any lifeboats the locals would be able to establish. The bigger the city, the larger each wave will be---in a big enough city, the early adopter bicycle wave may be 'locust worthy' all in itself. BTW, I think your map is probably not too far off the mark---with a few caveats.
Particularly in the Western US, not all miles are created equal---particularly when you've got to use muscle power to travel them. So the circles will shrink in areas of difficult travel.
Salt Lake has a good chance of not making a death zone at all, depending on how faithful the Mormons have been in keeping their religious injunction to store food.
Iowa also may do pretty well, based on the sheer amount of food there (corn has basically taken over the state), if and only if they can control the choke point bridges across the rivers. They do that (as they did in the books), and they're golden, relatively speaking.