Not only would you not be "assisting the legal process", you would almost certainly be breaking the law because you'd be denying people access to accounts without any legal authority to do so and without any conclusive evidence of who owns those accounts.
I don't know that miners are under any legal obligation to carry any transactions at all. Therefore, they can pick and choose. If they choose not to carry transactions involved in such a large criminal activity, that would strike me as reasonable, at least until the matter is properly settled in court.