If SI has sold any shares this scenario would be the only one I could imagine, It would have to be a delay or something SI really didn't like otherwise I can hardly imagine him selling any shares, he sees the upside here just as well as we do and he has had a lot more money invested than any of us.

If POET wanted him out of the BOD they could do that but he would still not need to sell his shares.

At this point, it is really hard to say if any of this is true or just a guess, personally I think there is to much potential here fo SI not to be involved somehow.