I agree. This was probably for internal consumption, to show the lefties El Presidente won't be pushed around by the gringos.
First I've read this: the Chileans were also involved in a shoving match with Chinese bodyguards accompanying Chinese President Hu Jintao. The Chileans won that round:
http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2004/11/22/wchile22.xml&sSheet=/news/2004/11/22/ixhome.html
"... Mr Bush waded into a crowd of Chilean security personnel to rescue his own chief bodyguard, Nick Trotta, who was being prevented from following his boss into a dinner for Asia-Pacific leaders, part of an Asia Pacific Economic Co-operation (Apec) summit that preceded yesterday's brief state visit.
Mr Bush, hearing Mr Trotta's frantic protests, reached over two lines of people to grab him by the lapel, telling startled Chilean security: "He's with me". Mr Bush then walked into the dinner, shaking his head in disbelief, and straightening his right shirt cuff.
Chilean guards were also involved in a shoving match with Chinese bodyguards accompanying President Hu Jintao at the Apec summit, successfully preventing the Chinese guards from following their head of state into a meeting with Mr Lagos."