No... try to copy some mod and publish it as your own and see what happens.
What do you think will happen? At worst, it'll be down voted into oblivion, maybe PDX will even pull it down. If some ass hat decided to take my work in Ancient Religions, integrate it into their own thing and not give me credit, there's literally jack-all I could do about it but call them out on it.
The only way you could actually own mod content is if you make content separate from PDX, e.g. a book, story, whatever, and then base your mod on that. That's the only situation where PDX doesn't have content ownership. Again... e.g. AGOT.
Intellectual property referenced by a mod is not the mod itself, so obviously.
We don't have the legal standing to grant or deny other authors permission to use our work (with the exception of art assets, of course).