It's illegal already to explain to setup a secure hidden service on the Tor network? I don't think this discussion is only relevant to criminals. There are a lot of places on this planet where this information might be useful.

I don't support the Silk Road - never used it - I don't even use Tor a lot by myself. But if someone is coming at me and tells me that this information is forbidden I'll get angry.

It's not like there is a drug problem besides Silk Road already. It's likely safe to assume that illegal drugs are consumed in near distance to your and my place right now. I don't think the Silk Road is a good place but it's likely better than your shady dealer on the schoolyard. If you ask why people use drugs than take a look at society at large.

What exactly is illegal here? I'm also not located in the US.