From the site:

  Years later I found out that my new knot was not new and that I had simply re-invented an existing knot, which appears elsewhere under two different names:

  “Double Slip Knot” (#1219) in “The Ashley Book of Knots” by Clifford Ashley;
  “Seaman's Shoelace Knot” (or “Seemännische Schuhbandschleife”), which appears in the German book “Knoten, Spleißen, Takeln” by Erich Sondheim.

I'm pretty sure knot techniques can't be copyrighted, so nobody owns it or has the exclusive right to name it. Someone can call it the Ham Sandwich knot if they want. Who cares?

Besides, I'm pretty sure Ian has done a lot more to spread the knowledge of this particular knot than anyone else in history.