I think he jumped the gun and misread a couple of scenes that he thought debunked it. He went from debunking the theory on Twitter to discussing the theory as a postscript to his episode reviews to now focusing on the theory for the entire piece on episode 5.

http://www.hitfix.com/whats-alan-watching/review-how-westworld-may-be-acting-too-clever-for-its-own-good

And I disagree with his take about twists. I felt like the moment we saw Clifton Collins Jr. reappear as El Lazo, it was supposed to me an A-ha or WTF moment? I don't think it takes away at all from the show. If anything, it adds to the William story since we're seeing how he's turning rather than just watching a goody two shoes wandering aimlessly around a theme park.