Does that matter? There was nothing drug specific about the site implementation - you could sell anything you wanted to (gold, collectables, etc).

He provided a system that could be used as a valuable service for legal activities. It could also be used for illegal or banned activities in various jurisdictions.

I'm just saying that it's a dangerous precedent to say that anyone creating a communication or transaction platform can be held liable for conspiring with users who use it to commit crimes.