He was obsessed with the place for years apparently. Because they reported something which he did. It was his own behavior which initiated it all.
I've seen this kind of 'hate obsession' before in my own life. Hate gives some people a reason to live. I ran into an old girlfriend years ago in a mall. She said, 'I guess you weren't ever expecting to see me again. I bet you spent every day hoping I would commit suicide. Well I didn't. And I won't. I'm going to live forever just to spite you!'
I honestly didn't remember her name. Hadn't thought about her in years. But people with a hate obsession always imagine that you think about them as much as they think about you. Even though you have forgotten all about them.
I'm sure this nutball imagined that the newspaper was reading his posts everyday and that they were as obsessed to 'get him' as he was to get them. That is usually the way hate works. In his warped and delusional mind, he likely thought he was acting in self defense, even though nobody at the paper even remembered who he was.