First of all, I don't see that he was calling you stupid. Remember, he actually had seen the test and all of the questions on it. If the entire test was one essay question asking you to detail the differences in the economic economic situation of the colonies during the American Revolutionary War and the states during the American Civil War, and explain how each contributed to the eventual outcomes of those conflicts (with a minimum answer length of 2 pages), and there was nothing else on the test, he would have been perfectly correct in assuming that it could not be completed in five minutes, regardless of how smart you are. Also, you have to realize that a substitute generally does not have the leeway in making decisions that the regular professor does. If the professor told him that the test would take a full hour-and-a-half, and that anybody arriving late was not to be admitted because they wouldn't be able to finish, then he would have to abide by that decision.
Also, nothing personal, but if you expect to have even a chance at convincing the professor to allow you to take the test on Monday, you're going to need to lose the ego. People are going to say things and have attitudes that you don't like, but if you want them to bend over backwards to accomodate you, then you will have to do the same.