I wonder if this has to do with the fact that, since Watsi is a nonprofit, pg can still lay claim to the rather unique boast of not serving on any company boards. (This is as opposed to accepting the position simply because he thinks Watsi > other startups)
Non-profit organizations are still companies. They are required to retain their revenues rather than distribute them as profits. From Wikipedia: "Designation as a nonprofit and an intent to make money are not related in the United States." (http://en.wikipedia.org/wiki/Nonprofit_organization)
