An other equally plausible would be that the silk road was a false flag operation, run by a undercover unit. Nothing points in that direction either, but hey, it "could be" right?
From Reuters (http://www.reuters.com/article/2013/08/05/us-dea-sod-idUSBRE...):
> The undated documents show that federal agents are trained to "recreate" the investigative trail to effectively cover up where the information originated, a practice that some experts say violates a defendant's Constitutional right to a fair trial. [...]
> After an arrest was made, agents then pretended that their investigation began with the traffic stop, not with the SOD tip, the former agent said. The training document reviewed by Reuters refers to this process as "parallel construction."
> The two senior DEA officials, who spoke on behalf of the agency but only on condition of anonymity, said the process is kept secret to protect sources and investigative methods. "Parallel construction is a law enforcement technique we use every day," one official said. "It's decades old, a bedrock concept."
> A dozen current or former federal agents interviewed by Reuters confirmed they had used parallel construction during their careers. Most defended the practice; some said they understood why those outside law enforcement might be concerned.
> "It's just like laundering money - you work it backwards to make it clean," said Finn Selander, a DEA agent from 1991 to 2008 and now a member of a group called Law Enforcement Against Prohibition, which advocates legalizing and regulating narcotics.
Given how they talk about parallel construction, it certainly sounds like it's not an uncommon technique, so do you think it's so implausible? I'm not going to say they did or didn't use it, because the simple fact is that I don't know, but given that "Parallel construction is a law enforcement technique we use every day" that is "decades old, a bedrock concept," it doesn't seem too implausible that they would use it in such a high profile and important case.
But in the mean time, one should not jump to it directly when more simpler explanations are available. Using undercover cops to entrap drug sellers is even older, and even more common method than parallel construction. It also extremely simple and effective.
I would also suspect, that entrapping a first time offender, an 47 year old administrator who sells drugs anonymously on-line from his home, to not be very hard. Especially if the undercover cop could impersonate flawlessly established "trusted" drug sellers by taking over their accounts, as it seems to be in this case.
All points toward parallel construction as an something that might had been, but in this case, is less likely to actually have happened.
One could argue that the entire NSA program was such a conspiracy theory until Snowden.