Yes, I understand this idea, and it is what I mean when I say that the rules of operation of the mixer invalidate the link -- in reality -- between the coins that you got from a mixer (post-mixing) and the coins that were given to the mixer (pre-mixing).

But the protocol doesn't reflect the reality of the mixer; the mixer is built on top of the protocol. Within the protocol, those coins are still linked, allowing perfect tracking of coins as they pass through the mixer.

You can argue in court that your kingpin coins aren't really kingpin coins, but you'll always be hamstrung by the evidence. What you really have are plainly-labeled kingpin coins and an admission to purposefully receiving contraband.