It's not him they are using facebook because it is the largest database of identity as mentioned on the front page of the site.

"Registration for the initial direct signup program will be done via Facebook. We are using Facebook as our initial login methodology because it is the largest database of identity, and our goal is to reach as many people as possible with our educational programs before running out of funds. Therefore, we need a system that allows us to screen out duplicate or spam accounts.

We will set up a website where anyone can come and register. We will also make reasonable best effort to screen out fraudulent accounts or people with multiple Facebook accounts. Once the direct signup program has commenced, the Foundation will begin work on alternative channels for distribution of stellars, including SMS and other online channels, in order to allow more people access without having to have a Facebook account."