What will happened to those who use the mixer previously. Is there a chance that my Bitcoin will be connected by Bitcoin use from money laundering or we are still safe? I use Chipmixer every week to mix my coins. Its sad to read this bad news. 
Agreed. This is very much similar to how the government has arrested Tornado Cash's developer for creating a tool to protect someone's anonymity and privacy. I reckon if a car was used by a criminal to kidnap someone, the government cannot arrest the car company or if a cellphone was used as detonator for a car bomb that killed hundreds of people, the government cannot arrest the cellphone company.
And yet, in the case of Tornado Cash, hundreds of millions worth of different coins linked to the mixer in one way or another were frozen. This was generally a blanket move. This wasn't just done selectively to suspicious wallets and addresses. This included funds of innocent and unsuspecting Tornado Cash users.
However, the argument remains the same. The government does not have the right to arrest the creator of the knife if his creation was used to murder someone. The government should arrest the murderer. I am shaking my head why there are some people who argue that the arrest and detention is acceptable because it is not.
Well, views differ. Apparently, your view isn't shared by the government. It is unfortunate, however, that the government is the one that is more powerful than you. If you think that they don't have the right to do this and that, but they don't agree, they will prevail.
So whether you think the government does not have the right to arrest somebody who is just writing an open source code, Alexey Pertsev is in fact still in jail right now. Whether we believe that starting a marketplace is not a crime, Ross Ulbricht is actually rotting in jail until today. So while we all agree that providing the people the means to protect their privacy isn't a crime, this Nguyen could indeed end up in jail as well.