The arena was certainly not empty nor even half empty, and it was not clear that the president was even on stage when the picture was taken.
Maybe not in 'that' picture, but another one showed that the upper section was 'darkened' for a reason.
Using a simple graphics editor to lighten, without changing any content, the results show many empty seats in the upper section:
![Photobucket](http://img.photobucket.com/albums/v71/Tomguy/2012%20election/Obamakickoff2012.jpg)