The probability you would be sued by the IP owner is, in fact, very low, unless you upset some notorious player like Games Workshop (which loves to burn money on destroying people who create free advertisement)
Problem is that if you try to seriously enforce it, your site will be bombarded with the fake reports to take down the content.
It happens on the Youtube right now, and was for the while.
Videos are taken down frequently based on the made up claims that might not even involve the actual IP owner, but abuse the mechanic of three strikes to straight away attempt to delete the competition if any report is taken seriously.
And this is what you aim to create here.
It's like review bombing on that site, but with documents...
That's what could happen, and is happening elsewhere right now.
It doesn't even need to involve actual IP owner. It's not uncommon for the hobbyist sites to pay the lip service to the law, offering to take down the offending work, respecting the copyright law and the right of the owners, and so on, but who actually enforces it? Seriously? No one. They just have to say they respect the law, because, in all honestly, it's the much greater offence to claim you don't acknowledge the state government. So everyone respects the copyright, and writers fan-fics, and some kid gets free 10 dollars, but that's pretty much it. Nothing else happens. Usually.
However, if it is actually enforced?
Seriously?
I deleted my fan-fiction ... fine, hope you are happy, it wasn't that good,I am not even claim I am a competent writer, but ...
But do you realize what a cesspit you create with this? It's straight away malicious.