The article notes near the end that the authors think the diameter of the hexagon is tied to another constant, so I would guess that they kept the full hexagon

The article notes near the end that the authors think the diameter of the hexagon is tied to another constant, so I would guess that they kept the full hexagon because studying a regular polygon has advantages that studying a wedge doesn’t — so, since they aren’t done studying this all yet, perhaps they have causes to consider a full hex rather than a wedge that are still WIP.