As to challenging this designation, well, where to start? The bar for challenging an administrative rule is a very high one: the rule must be "arbitrary and capricious". These rules don't strike me as such. In any event, the cost of challenging the rules would likely top a million dollars for competent litigators in the field to bring such a case to completion.
Do you think the recent
Arlington v. FCC decision increases this deferential standard of review, or just extends it to an agency's interpretation of its jurisdiction, and in either event, does it have any likely relevance to Bitcoin regulations?