The fact that someone pulled over at an overlook just happened to see him go down and actually have the presence of mind to realize that he was in trouble and to go help is just 100% pure horseshit luck.
Not to mention that the driver had a shovel in his car. If I was the driver and wasn't on my way to do a little BC riding I wouldn't have had a shovel in my car. I doubt hand digging would have done the job. Crazy situation.