You obviously can't cold call an attorney and ask for help laundering money. But if you find a money laundering operation through the proper channels, then it will likely involve a law firm somewhere that's facilitating making it properly legible to the system - setting up less-than-truthful companies, generating copious fraudulent documentation, etc. If anything attorneys' trust accounts should be receiving more scrutiny rather than less - using your account to handle money held in trust for someone else is generally something that sets off compliance department alarm bells, and for good reason (well, as good of a reason as there can be in the context of this topic).
I suspect the bar would not allow that.