I disagree with you a little, if you knew that all but say 500 million share were held by people who were holding long, it would give you an idea of how much was being traded and flipped. There is a supply and demand factor that affects share price.
Now whether or not you can ever get a firm grasp on that is a completely different story.
I believe that he only was counting the holders. A lot of it is based on trust that people are being honest. The margin of error is probably at least 5%