I know a man who did a similar thing at a speech by Lyndon Johnson while Johnson was the president. He went to the speech with the idea of listening to it and he noticed that the people setting up the stage were a bit disorganized so he took charge just for the heck of it and ended up sitting on the stage in a good seat during the speech. He was a young cop at the time, but not in any way affiliated with the president's security detail or the arrangements for the speech. He was dressed in a suit and tie, not a uniform. He's a cool old guy. Lives in Georgia. Has a few other interesting stories too.
He told me that story when I was a teen as an example of how important confidence and command can be.
