It works for creating a standard nonautotile out of an autotile slot which was what I was commenting on. Basically no matter which 4 16x16 tiles it chooses all the ones for each corner are identical to each other so it can't create anything but one 32x32 tile.
http://blog.rpgmaker...of-an-autotile/
Look at the tutorial again. Remember that an "A" minitile will ALWAYS be in the top left of the composite tile. A "B" minitile will ALWAYS be in the top right of the composite tile, etc. Because of this you can overlay an entire 32x32 tile over the entire autotile and it will work as a standard nonautotile.
(And I'm glad people are still reading that tutorial, I keep meaning to make a part 2 to it that covers the other styles like water and waterfiles)