There's no guarantee you would use your own node. It's entirely possible that the police could find actionable evidence on his systems even if the initiating evidence wasn't actually because of him. Sort of like a police office seeing what looks like a beer bottle in a drivers hand and pulling him over, only to find it's a rootbeer bottle, but the driver actually is drunk.

To make it fit this case, the police know it's root beer before they pull the driver over, but they do it anyway.

To make it fit this case, they got an anonymous call about drunk driving with a car that fits the description. It looks like it's just a root beer bottle, but it's not out of the question (IMHO) to stop the driver and make sure.

If "root beer" is tor traffic, and "beer" is illegal non-tor traffic, then they got an anonymous call about the driver holding a bottle. No evidence of drunkenness.

Well, not quite, but eh I can't make it perfect, it's a throwaway analogy.

No, the police showed up because a a report of child pornography was traced to his ip. An actual crime was reported and followed up on. Let's not lose that point, it's important.

An actual crime, but they knew they had no good guesses about who committed the crime.

More apt, they saw him swerving in his lane, while driving with a root beer bottle.

Ah, the joys of Gettier.

Eh, its a yomi thing. At level 1 you want to run a node because the police will ignore you. It doesn't become a bad play until the police are on level 2.

More like, they'd do CP and run a node in the background as an afterthought just to cover.