Yeah, there's nothing quite like a fundie upraising to make you realize that parents do NOT always know best for their teenagers.
I didn't have it as badly as your friend, but the list of banned books in our household was quite long. I'm certain I would NOT have been allowed to read Harry Potter or anything similar. Promotion of magic in books leads children to Satanism, dontcha know.
I rather imagine anything criticizing war, the government, etc. would also have been right out.
I actually know a guy at work who doesn't let his teenagers read Harry Potter. I suspect they spend a lot of time "researching" at the library.