Not really, Ispolkom, take a look at any zone boundary and you'll find that they can move the line wherever it suits them. They don't have to draw the line directly on the CONOs route, and even if they did then they could make the zone boundary only apply to CHI and NOL, not to the intermediate stops. It isn't an issue of geography.
You also must take into account the map was written with the old system, notice that Fostoria, OH is a border city, as well as Pensacola, two cities that don't currently get Amtrak service. Pensecola is odd because it juts out pretty darn close to NOL, whereas TOL, Fostoria, CIN, and ATL fall just around the same place on the line-- Pensacola does not. Reason? Possibly to make sure that if/when we get NOL-MIA service, it is two zones as well. This also means NYP/WAS-NOL is two zones.
It isn't NYP/WAS to CHI it is the whole LD system outside the NEC. Anybody traveling to, or from, the NEC on an LD train (except the Silvers) will have to pay two zones no matter where they go West, unless they get off in a smaller area.
Keep in mind sleepers make up a tiny portion of AGR redemptions (the vast majority being NEC related), I highly doubt AGR ever put a ton of thought into this one.