Let's suppose a hacker is reading this. What will be his course of action now. Since the Authorities have asked mixers to keep an eye on this address and do not entertain any request of mixing from this address, the hacker can easily create one or more brand new bitcoin addresses and move the funds to those newly created address. Then he can move the coins from that address to the mixers and mix the coin without any issues.
I'm not talking here about an already hacked scenario, but whenever such an incident takes place and the higher authorities immediately start contacting the mixers and if the mixers are, at all, interested in helping them out by stopping the mixing of the coins from the hack and return them to where they belong. I know nobody would use them if they do this, but isn't it good to stop the bad before it becomes worst?
Secondly, no government have officially allowed to operate the mixers and therefore they have no legal right to dictate the mixers on what to do and what not to do.
I never said that any mixer is allowed to operate legally and that nobody can tell the mixers what to be done and what not, but does that mean that the government officials can't even try to contact these mixers to at least try their 0.01% chance at stopping the scammer from completing his crime and get away with the money as well?
Anybody here who thinks that using monero is the only option that is left for the scammer, then I believe that even for that option to become available for him, he first needs to settle his Bitcoins either through mixing or OTC and nobody would be able to complete a $300 million deal in one go (there's a chance that even the scammer gets scammed here) and if he goes through a mixer, I believe that a mixer may take some steps to stop this person.
Now, those talking about creating various new Bitcoin addresses and moving the coins there, every single transaction can be traced easily.