That is not at all the same thing. Why would police want to go poking at the ISP in your example if there was no reason to believe the ISP had done anything? And even if they DID want to, how would they get a warrant to do so with no probable cause? As much as people would like to believe that running a TOR exit node makes them an ISP, the technical and practical realities mean that at least at the start, YOU are going to be suspected of any wrongdoing going through your node. The legal system will protect you eventually (as it did in this case), but you're running a service that, by design, makes it look like a bunch of strangers' Internet traffic is coming from your computer. If police want to investigate that traffic and you tell them "sorry, I'm just running TOR" and they just take your word for it and go away...that would be some pretty incompetent police work. Running and exit node is legally protected, but expecting it to be totally hassle free is just silly.