I think it's more complicated than he forgot or his zone judgment isn't good. By the looks of his chase tendencies, his knowledge of the zone probably isn't as good as many good hitters. But for the batter everything happens so fast, you're tunnelling in on the ball as it leaves the pitcher's hand trying to pick up spin and all that stuff. When you misidentify a pitch or get fooled, as Chourio clearly did, it throws everything off--including your ability to judge where the pitch landed. The pitch bamboozled him, ended up doing something completely different from what he was expecting it to do, so why shouldn't he assume the ump got the call right? The whole thing was awful to watch, made Chourio look like an idiot, but I think that's more a reflection of a failure in pitch recognition and its downstream ripple effects.