Is it even partial slavery if he doesn't have voting stock? This article is cute in parts and all, but I really question the legality (and definitely the morality) of this.
That probably changes things then. I mistakenly assumed that his shares were actually non-voting shares, and that he had no contractual right to vote. If he has voting rights but is just abstaining from using them, then that's quite a bit less crazy.
I'd love to see a source for that. I've browsed quite a few of his websites and read several articles about the project, but I've not come across him saying he has voting shares that he promised not to use.
I doubt there is any case law surrounding voluntary servitude of this nature. I'm not sure one could call this slavery since he voluntarily entered into the relationship with his shareholders. It would be an interesting case, no doubt.