We as a community can reject these coins all on our own.
That's quite a good idea and it is your privilege to accept/deny anyone's coins. Good luck with doing that after coin mixing transactions. I also hope an organization that you support doesn't get it's coins "banned" in such a way.
As long as you don't mess with the network I don't care what anyone does on an individual basis, so I'm ok with your concept, but not necessarily support it.
I hope you do realize coin mixing won't stop reverse tractability at all.
We already know the BTC address with the coins, and we can see where they go after that etc.
No amount of coin changing will stop tractability.