Some people's only purpose in life is to server as a warning to others. This wasn't a porsche 911 handling issue - the car was straight and in control. He simply somehow wasn't able to stop while driving in a straight line.
I've never tried an autocross and probably won't in the future. Mainly due to a lot of standing around and only getting a few 40 second runs but this certainly doesn't help.
Also don't rely on the internet or word of mouth for information about being covered in a timed event in a parking lot, or a driver education on a big track. I would speak directly with your insurance agent. Even if they do cover your mistake, you most likely be dropped and end up paying a higher rate with another carrier.