I don't know. Many people do odd things for no reason other than their own curiosity. For example, there's the guy making soylent in an effort to create something that lets him avoid eating. Many would ask "why?" while they say "why not."

Also, selling only 10,000 shares lets him back out if he where to encounter a problem (such as one person buying all his shares and then demanding he act in ways he's uncomfortable with).