Many mixers were seized but it is a first time I read documents mentioned Bitcointalk directly like this by Chipmixer seize.
You're misinformed. Posts on bctalk have been brought up in many legal cases, including several high profile ponzi scammer cases. Yet ponzi scammers are still here and not banned, even one you quoted in OP.
when mixing sites get banned here for promoting money laundering
Nobody promoted money laundering. You're hypocrisy is just wow as you walk around promoting a casino which has been
magnet for money laundering long before mixers ever existed. .
Step 1, get a dunce hat.
Step 2, put it on.
Should forum admin consider to stop all campaigns related to mixers?
No not without a court order. If they decide that, they should move to end sig campaigns all together.
Bad people use mixers, bad people use casinos, bad people are everywhere. Why not shut it all down??
