The Supreme Court has ruled at least once that a challenge to the Constitutionality of a law is not an adequate defense to
willfully breaking the law. If a defense is a complaint about the law, rather than being based on what the law says, then the defense is worthless, and the jury will be instructed to ignore it (cf. Cheek v. United States, 498 U.S. 192).
I don't know that this is what we're seeing, and if it is the Judge could be clearer.