Did he explicitly require that activity for participation? Just because it was thought by some to be an optimal medium for that activity, doesn't mean it was there for that explicit purpose. It was a website using TOR. TOR was created by the military. Neither the inventor of websites, nor the inventor of TOR created them for the purpose of illegal activity. If he was a fan of that activity, that also doesn't make it any more illegal than the publications available under the protection of the First Ammendment. If he participated in the activity of selling illicit goods and/or services, that would be another matter. Besides, these goods and services are not illicit everywhere his website served. His biggest mistake was being a US citizen.