I'm afraid that I have to agree that this is an extraordinarily ill-advised plan, and will only drive darknet users to encrypt their communications, as everyone else has noted.
They'd be better off cutting deals with YouTube and the like, getting ad revenue, and making sure the legal sites are ranked higher on search engines than the free sites. I think a great many people don't even know they're getting content illegally. They just search, click, and watch, listen, or download as indicated. Finding a way to make money from this already-existing behavior is likely to be a lot more fruitful than trying to change said behavior.