I agree with your conclusion (life isn't straightforward, do what works for you, don't trust "secret to success"-pushers), and having never really read zenhabits before I'll believe your premise that a lot of the content there contradicts other content there.

Looking for the least-malicious way of explaining that though, you could say maybe the author is someone who is able to change their mind, even if it makes them look dumb. I think that's probably a good thing.