Just because something is illegal doesn't mean it is wrong. There are a lot of sociopath control freaks that want to dictate morality to the world, or to have power and control over others. There are many "crimes" that one might participate in that are perfectly valid business transactions such as consumption of controlled substances and prostitution. Right and wrong transcend words written on paper. One might argue that enabling the freedom to participate in these markets safely is extremely ethical and those attempting to restrict these markets are the criminals.

I think you need to explain why money laundering is unethical. Because there are plenty of laws passed by various governments that many people feel would be unethical to follow.

To use an extreme example, was it unethical to hide jews from the Nazi's?

Who says that everyone who wants privacy necessarily wants it for criminal purposes?

I'm guessing the intent is to say that anonymizing the source of money per se doesn't seem to do anyone any harm, much like accepting cash as a form of payment. The problem is when people use such channels to avoid detection of crimes by law enforcement. We have to decide as a society which conveniences or defenses of privacy (anonymizing the source of money being one) are worth sacrificing to enable better law enforcement.