Except it wasn't a lie. It turned out to be the truth, and even when that little fact is ignored, the film never disproves it in any way. Isn't it funny how sometimes what seems so "obvious" turns out to be so completely wrong? Problem is, he did call him good. That's still canon. So by definition he was what Obi-Wan would call good. It appears that Anakin wasn't what [someone] would call good. But that [someone]... it wasn't Obi-Wan.