Kind of petty revenge. But then, I don't buy the "this will just give him more reasons to crack down on the Internet" line of thinking, either. He didn't screw over Title II protection of the Internet because he was "cracking down" on anyone- he did it because he's a tool of telecom companies empowered by a boss who thinks that anything that pisses off people who don't like him must be a good idea, even if it entails setting his own house on fire.
Pai made a crappy, but entirely predictable, decision. This is Anonymous' crappy, but entirely predictable, reaction. If I thought it might make someone with the power to enact change re-think their policies on Net Neutrality, I might be tempted to wonder if the ends justified the means, but it won't. I'm somewhat sorry for Pai's family, who don't deserve blowback from their relative's decisions or the reactions to them.