He surely invented "Ian's Knot" (the term for it). Even if there already existed a knot tied the same way, if people didn't know it by a name, surely there's some benefit to having a name for it?
When you pull the two string ends of a standard knot at the same time, the loop shrink and pull out of each other at the same time. Just figure out how to do that backwards and you probably have Ian's Knot or something very close.