My friends and I debated the wall a bit. We all came to the conclusion that they did it for video purposes. They didn't want the cameras to be shooting sparsely packed stands. Most people were content to stay up on top by the railings, which is what this photo doesn't show. There was actually a floor above the gym that a lot of people were watching from (including myself).
It was an amazing atmosphere, and my first Ron Paul rally. The people were all so kind. Liberty was definitely in the air. Also, before Ron Paul took the stage a guy gave a great speech on the importance of voting. He reminded everyone that attending rallies is great, but it doesn't do anything for the campaign if they don't vote.