What do you think the best way of proving you're not a terrorist or a threat? Personally, I think making a video in which you threaten a major player in the video game world, leak information involving salary and personal numbers/email addresses while at the same time hiding your voice and real name is the way to go; you can't get any clearer than that, "we have NOTHING to hide!"
So Activision portrayed a group with a history of illegally invading certain areas of the internet as a group that may one day be able to justify hijacking government weaponry and vehicles because "they're doing it wrong," is it so farfetched? Anonymous have time and time again performed acts which bug the hell out of the people they claim they are acting for and then tend to distance themselves from the act when things get too heavy.
And now they're offended that they're being portrayed in a negative way. Bless them.
