Two things about that which strike me as completely backwards.
A) American Congressmen, especially Republicans, vehemently oppose any concept of "international law" treaties. We still haven't signed onto the fucking International Court system yet, what makes you think any of those knuckleheads would agree to a law where all you have to do is accuse someone of piracy (and again, accuse them TO WHOM?) and your ISP has to shut your Internet off for a year.
B) They also represent the actual law-enforcing people in a country, who will also vehemently oppose being told what to do by some foreign non-governmental think tank, because they already have their own shit to worry about. Any such system of "Report and Automatic Lockdown No Trial Ever" will carry mountains of paperwork to keep them from getting their asses sued for false accusal.
C) There is no such thing as international laws being enforced at a local level. If this "treaty" were to be incorporated into American law, it would be by writing our own new laws that would comply with the treaty in some way. And ergo, would either have to allow for actual fucking due process or the Supreme Court would strike it down in a matter of weeks.
And D) Why does everyone assume that every government everywhere will always do whatever "Big Business, man" wants? The EPA exists doesn't it? And even so, ISPs aren't going to want a law like this, because they sure as Hell don't want to be shedding customers left and right.