Yes, that is true. It be up to Anonymous to refute it and any news organization worth a snot would get on Anonymous representative and directly ask for confirmation. That's why they where quick to say, "Hey it wasn't us." You don't want to be possibly viewed in that light in this time. This whole thing is making the regular news.
That's the problem, though - there is no "Anonymous Representative" to talk to.
Think of it this way - you have two teams, the Bears and the Cubs. They're both sports teams (i.e.: Anonymous). One team might be doing one thing (playing football) and the other team is off doing another thing (playing baseball). Sometimes, they might work together (i.e.: a charity dinner for a children's charity). Sometimes, they might be on opposite sides (who can sell the most tickets...). Often, they're not even in the same room and have absolutely nothing to do with one another. Now, you have coaches who can speak to the media and represent the team.
Except, with Anonymous, you don't know who the coaches are. And there's no way to verify who is and isn't an Anonymous coach. I could be one. My boss could be one. Your own mother could be one. You don't know and there's (virtually) no way to find out.
And if someone does come forth, claiming to speak for Anonymous, they probably don't.
And even if you did speak to the coach of the Cubs, it doesn't mean he speaks for - or even has the slightest idea - what the Bears are up to. Hell, he likely doesn't even speak for all the players on his own team.