That would entirely negate the MitD's massive "marking off wrong doors" Chekhov's Gun if Team Evil found the gate in this specific marked door. This is, essentially, the singular time the evil side hasn't found the gate before the good guys. Well, I suppose Girard, but the evil team was there before the good guys, they just fell for the double-bluff since it wasn't Team Evil because Xykon would've seen through that. Or at least decided to blow up the surrounding pillar and discovered it by accident that way.