He wrote Surveillance Valley. I think he's quite qualified to comment on it.
Dan Brown wrote Da Vinci Code, but I don't think he's qualified to talk about the history.
The Da Vinci Code is a fictional novel. Levine's book is well researched and he cites his sources. Is he despised on HN because he's Russian? That would be xenophobic. Is there something else about him that I'm missing?