See, I think there's an alternative explanation to this. Say you're in the airplane stall. You do your business, hit flush, but for some reason instead of a giant sucking sound sending yesterday's Taco Bell into the atmosphere it ends up doing the exact opposite.
BLAM! You're covered in ****. Can't see because there's poop in your eyes.
You stumble around in the stinky darkness, finally find the door handle and fall out, trying to find someone to help you.
But instead of thinking you need assistance, the flight attendants and passengers take it as a terrorist using a defecatory weapon to take over the aircraft. You're knocked to the ground and suddenly the story is that you're mentally unstable.
You'd be mentally unstable if you were covered in crap, too.