Cause even in tor it eventually leaves the network.
This data could only be known that it came from your direction, but also known it wasn’t you transmitting it. Anything beyond that is just a sea - it’d be like arresting a truck driver for unknowingly moving drugs buried in stuffed animals.
They’d essentially have to by hand arrest every single node that participated to the source - assuming that chain was never broken along the way - to get anything reasonable out of an arrest.
Most importantly this is all public knowledge, so after a couple essentially useless arrests attempts for unknowingly hosting encrypted data, I believe they’d have to back off