Sorry you were so freaked out, certainly not fun for you. To everyone else freaked out by the thought, please try not to worry. Although possible this is a rare occurrence.
I know I'm in the minority here but I'm excited to see snakes in the wild - including "wild" Disney. (Look at my username.) I grew up with snakes and have 3 as pets. I would have been tempted to take the corn snake home with me. They make the best pets.
Of course I know snakes and can tell the difference between poisonous & non-poisonous. I am disappointed that they killed the snake. Anyone in that position should know snakes better than that. A corn snake looks NOTHING like any poisonous snake.