He must have held. I believe if over 5% you MUST file if there are and changes in ownership (adding or deleting shares). So I think he maintained his % ownership and thus had no filing requirements.
Clearly I'm not a broker or SEC lawyer. But considering his nearly 15% stake in the company, you can be certain he did not disappear. Just look at the volume. There's no way he could have dropped out even if I am wrong on the legal disclosure requirements.
Sadly I think mblx has some poison pills which needlessly stop him from buying more.
FYI, I was the one who pointed out what was happening with Jack in my post on Mar 11, 2014 at 8:25 PM... I thought that I was pretty clear in that post yet I suspected that some of our shorts would run with it and try to make it look like there is an issue. Personally I'm glad to see that it's only an issue for those who don't know Jack :)
It does seem strange that the "Major Holders" sections do not show him as a major player. I saw on one major holder (Not institutional holdings, but individual) section (I think it was MSN) that there were some 3.3 million shares sold by major holders. If you Google "Jack Schuler" major positions held, you see a number of companies he owns 5%+, but no MBLX.