Did he actually sell the drugs, or did he just create a communications platform? Should all communications platforms be liable for what people do on them?
If you drive the get away car in a bank robbery and someone inside is murdered, guess what? You get to be charged as well.
He actually sold a ton of drugs too.. you don't need to raise these questions as unknowable hypotheticals, it's literally a google search away to find out. The first sales on the site were trashbags full of mushrooms that he grew in a cabin in Texas.