I think his point is that the same legal principle applies. TPB is clearly "in-league" with copyright violators. I will not weigh in on whether this is right or not, but it's obvious from their past behaviors (blog posts, etc.). They are guilty of "conspiracy to commit copyright violation".
I disagree that "the same legal principle" applies, but then I'm not sure we have the same principles in mind. It sounds like you are thinking about the concept of conspiracy in general, or contributory infringement. But that's not what I was referring to.
In my mind, there is a clear delineation between what is criminal offence and involves bodily harm ("illegal") and what is simply an alleged violation of intellectual property or contractual rights (e.g. "alleged copyright infringment").
When someone jumps from one to the other, as the commenter did, it is very strange. Because to me they are two very different areas of law with their own distinct philosophical origins. That's why they are almost always separated into a criminal code and a civil code.
There are plenty of examples of conspiracy to commit civil offences. Ignoring them and using an example from criminal law, and in particular homicide, one of the most heinous of all crimes, seems unnecesary. It raises the suspicion that either the commenter is using this example merely for shock value or that his knowledge of the law is very narrow and not well-informed.
I read you statement as you thinking he was making a moral equivlancy (conspiracy to commit murder was the same as aiding copyright infringement). My point was that he's not making a moral equivlancy, he's just pointing out that to say TBP is not culpable because they don't host the files on their servers is missing the point, at least missing the point as lawmakers might see it.
However, your statement "that's not a thing" is not entirely accurate: the DMCA's anti-tampering clause actually feels quite a bit like a law in the style of "conspiracy to commit copyright infringement". Specifically, it holds people who distribute tools that bypass protection mechanisms culpable, even if the primary use of that tool is not for copyright infringement (not so for the Pirate Bay), even if any and all marketing is for that positive use (not true for torrents: it is a rare torrent client that isn't marketing in a way that makes it clear "you could use this to infringe; in fact, here's a screenshot of another user doing so"), and even if there is a clear moderation effort and stance against piracy (again: certainly not the case with the Pirate Bay).
Of course, neither the Pirate Bay nor torrent clients are protection mechanisms, so AFAIK these laws would not and could not be used, and the DMCA is a US-specific law and these people aren't operating here, so I'm not trying to say they are already breaking this law (another reason to not go into specifics: they really aren't directly relevant, and it then requires this massive hedge to make certain people don't start arguing some nitpick of an example off into the weeds); however, it is a clear example of "conspiracy to commit copyright infringement" as a real law that has been used with real consequences in the real world in situations where people have committed not a single act of piracy.
Note: the closest I have ever gotten to being a lawyer was a role as the off-stage voice of the judge in a college performance of 12 Angry Men; what I know about this subject comes from running Cydia, the alternative to the App Store dealing in everything other than an App for jailbroken iPhones, which has had me deeply involved in the hearings to get DMCA exemptions. I thereby also watched with much interest the results of Sony's lawsuit against GeoHot, who happened to also have been the first person to unlock the iPhone and an instrumental player in various jailbreaks that were released, and his related-but-separate DMCA exemption that is currently going through hearings.
What that does mean, however, is that I'm on the other side of this: so if anyone (like "howcan") wants to make an argument that I'm somehow making some moral stance that contributing, even accidentally, to copyright infringement of others is as problematic as murder, I should really only have to go "seriously? you're argument is that I shouldn't call myself a murderer?". It also means, and I say this quite sadly, that I have a front-row seat to the effects of these laws: if you want to claim that these laws do not have any teeth, or do not take the overall stance that "conspiracy to commit copyright infringement" is a relevant idea, I thereby feel I need to ask how much experience you have in these matters.