I cannot see how you can "authorise" a crime by simply announcing where it is taking place.
If you actively encourage others to join in a crime, that would be different, but a link to a website does not constitute, per se, an active encouragement to visit or to use it, except in the minds of those who are paranoid about piracy.
Why don't they gratefully accept the intelligence they have been given by this lad and pursue the site owners who are thus exposed, the ones in fact who are actually committing a crime?
After all, he has stolen nothing at all, he hasn't even "handled" stolen property. He has in fact exposed those who are doing so.
It seems to me that the US authorities are paying lip service to protecting copyright by pursuing the easiest target, while achieving nothing in terms of catching the thieves.