It is unclear if the affected entity ever imposed sanctions or other form of punishment on the perpetrator (presumably they did notice that there was no longer demand for their silk in certain markets??). It also appears that the perpetrators promptly established a monopoly of their own (on the basis of somebody else's know-how which is also somewhat odd with today's eyes :-).
Somehow it is all predicated on very sparse communication between different parts of the world. The flip side is that in today's hyper-connected world you might be able to tell if a secret has leaked just by triangulation.