LogFAQs > #901660732

Eh, after researching a bit more into it and checking out their website/publications, I really doubt it's that group. Generally groups like these aren't really savvy enough about video games to even know what VNs are. They tend to seem to go after bigger, more mainstream targets like GTA games. Think about the kind of stuff the typical soccer mom would know about. They likely just monitor the news and saw stuff about Steam removing "porn games" and thought to claim credit for it.

As for who it might have actually been, rogue intern/employee acting on their own seems kind of likely. Either that or someone mass reported the titles somehow and a Valve employee decided to act on them, maybe not without really knowing their own content policy. Valve seems anything but organized to me.