I much prefer the original composition, because it all balances. The large dark hill on the right is proportional to the big bright area on the left, and gives the whole image the sense of depth and great distance. The reflected light on the hill helps to direct the eye back to the lighter side. Extending the view to the right, where the hill meets the horizon just keeps the whole view "grand".
The photographer wasn't asking for help, and doesn't need any. Keep in mind that this is HDR, so it took a lot more work than a normal pano, and a lot more "vision". Thanks to him for sharing this, and reminding me that I need to get out more, and work on HDR panos!