I'm pretty sure this technique isn't PUT UP A WEBSITE AND COLLECT IP ADDRESSES; they could be directly going after suspected pedophiles (IE, sending them a link through AIM). And either way, it's pretty possible that they have the web server set up so that it only registers IPs caught from a link they themselves have set up and not anyone who blunders into it - so that they're only catching people who see a link saying 12 YEAR OLD PUSSY and click it. They could only be setting up these links on pedophile networks even, so that the average net-user wouldn't find them.
There's not enough details in the article to be instantly alarmist.

That’s right, you have the young gaming with the old(er), white people gaming with black people, men and women, Asian countries gaming with the EU, North Americans gaming with South Americans. Much like world sporting events like the Wolrd Cup, or the Olympics will bring together different nations in friendly competition, (note the recent Asian Cup; Iraq vs. Saudi Arabia, no violence there) we come together. The differences being, we are not divided by our nationalities and we do it 24-7, and on a personal level.
We are a community without borders and without colours, the spirit and diversity of the gaming community is one that should be looked up to, a spirit and diversity other groups should strive toward.