"Render unto Caesar what is Caesar's," but when Caesar sees others seeming to not agree with him about what is his, he becomes a cruel oppressor. He will not easily give up his control over his subjects, and neither ought we expect it.
Mixing is a technique to obfuscate one's identity when considering transactions, which is as much a protection against tyrants as it may be an evasion of justice. It seems to me to be morally neutral, like owning weapons or driving cars. It is not the provider of the means but the user who should be held responsible, and that is the point. The DOJ is wrong for this.
