Greed betraying Father was organic and felt natural and the reader already had a deep interest in the character and his motivations. If this "mystery" traitor is really York, then that's kind of the opposite in every other way. Including the fact I have no reason to have any interest in York before this reveal, and this "mystery" has felt more like just being led around by the nose by Oda for no reason other than to pad out the arc.This would literally mirror the traitor Homunculus in FMA. Makes me think we should have seen it coming sooner.