You are correct. Anything else is not the problem for which Marilyn Vos Savant's solution is correct. But her original presentation of the problem in Parade m

You are correct. Anything else is not the problem for which Marilyn Vos Savant's solution is correct. But her original presentation of the problem in Parade magazine did not state whether or not Monty always opens a bad door. If he does not always open a bad door or does not use some method uncorrelated with whether or not the contestant has already selected the door with the car to determine whether or not he will open a bad door, Marilyn's analysis is wrong.