ManipUni said:

How did the paper get his personal information?

Investigative reporting

As w3bbo said this has nothing to do with the government at all, the news paper's interest was piqued for whatever reason, and they wanted to reveal his name. He sued to stop them. And lost.

Government didn't drive it, government didn't care, and the ruling does make sense. If you start pinning up manifestos on church doors you have no expectation to privacy, why is blogging different?