Yes, it's possible, which is why i am not necessarily saying it's copied from me. However, I freely discussed the idea with many of my colleagues, including when i worked in MS where Mr. Bennet works (same city and we share many connections on LinkedIn) and so I won't be surprised if the word spread enough in 9 years to affect his thinking even if he did not copy it directly.
Beyond that, to get to that detail (chain link length, analysis of average link length etc) you would need to spend a bit more thinking than writing a page long summary in slashdot post, and yet there is nothing more, not a blog post, not a sourceforge project, nothing from the author of this slashdot blurb that shows he has been developing such system. I spent almost a year developing and refining this system, analyzing attack vectors and how to address them, and it sounds extremely unlikely to me that someone would follow exactly the same route, come to exactly same detailed conclusions without either spending much more effort than a slashdot one-pager or being influenced by other work.
