Exactly. If I had the inclination (and access to child porn) I could probably put child porn on half the servers on the internet. It wouldn't be hard to write up something that automates it and uploads CP in every file field it crawls online, or even just post a base-64 encoded version in the comment fields of any site that doesn't allow file uploads. In fact, that would be even better, because in your typical CMS, text content is just marked as deleted but actually kept there forever.
I wouldn't be surprised if half the webservers on the internet didn't already have CP on them in exactly the same fashion. Even after moderating an image it's generally not deleted (in fact, isn't that technically illegal? You find someone uploaded CP to your server and delete it, you've just destroyed evidence in a crime).
So basically, any server at any time can be taken for claims of CP.
But then, that's pretty much exactly what prosecutors want.