... and had too much time on their hands. Seriously, when something is offending me, I contact the author and webmaster first. Not take the whole cluster down.
It is actually cheaper to launch a DDoS attack then to talk to the webmaster, if you already control enough zombies and value your personal time highly enough.
The attack might have been launched for the fun of it, too. Why not, when you won't be affected personally?
Maybe they did to no effect, or maybe the content was of such nature that they didn't want to draw any extra attention to it. Pure speculation of course, but no matter the reason, they achieved the intended end result "efficiently".
