>>718583289
>>718583468
>>718583396
>>718583450
He actually could have a case depending on the contents of the mod. You do not necessarily cede all rights, copy right included, on an intellectual property just because part of it might be in violation of someone else's copyright. For instance, JK Rowling could not go online, steal one of the hundred of Harry Potter fanfictions and publish it just because it uses here IP. The writer of said fan fiction actually would legal be able to claim the rights to the parts of the story they created: their prose, any original characters, any original settings. This is actually a good thing to prevent abuse of the system. For instance, Capcom recently had a texture artist get caught using copyrighted textures in RE8 without permission. Would it really make sense to cede all the rights to Resident Evil to the artist who made the stolen textures? Of course not. It's the same situation, people own the pieces they create even if it's a part of a larger whole that might be in violation of someone else's copyright.
So in this case, the code is likely largely safe to steal. If it's edited code from the original game at least, entire blocks of code provably written from scratch by him could be an issue. The bigger issues though is any art or story elements he's added. If they are his creations he absolutely could have a case. It's a very messy legal grey area though so I imagine most sites legal would never touch this shit.