The point would be that nobody would give any credence to the opinions of a 12 year old boy, or a fat plumber from Sheboygan. Most people, even, tend to give less credence on military subjects to politicians who never were in the military. By pretending to be a soldier someone could add weight to their opinions that otherwise might just get ignored. Undoubtedly the author believes whatever he wrote, but whether his opinions should matter is clarified by his occupation, or potentially what he pretends his occupation to be.
Maybe it wasn't a kid. Maybe it was an adult writing it from the comfort of a cushy chair in comfortable home drinking fine cognac laughing at how easily it is to make people think whatever they want. Or someone like him. Someone who wanted to make Kerry look bad. He's not screwing with people like me - he's trying to screw with people who will think it's true. I think it's bogus. You think it's true.