How do you get that impression? His 2003 work talks about his fascination of propaganda and how it might be unethical to persuade someone using technology for malicious purposes. He also has old lecture videos that give the same impression in a more academic-neutral light:
It's been well over 20 years since his work started was published. That's a full generation to see the effects of technology and mainstream adoption while comparing it to your life's work. I think it's fair to see someone decry the state of affairs when they were already on that side of the fence. It's quite unfair to attribute his involvement as something malicious though. Behavior science itself is already an ethical dilemma.
Maybe the 2007 book has something else in it, but I always got the opinion that famous founders simply attended the class and may/may not have used what they learned in it. Not that he was involved outside of it. But who knows who is in each other's pocket. I still like the guy as his message hasn't really changed.