It wasn't taught at all.
The fact that Luther's drunken rantings became foundational elements in the thinking presented in Mein Kampf is a glaring omission in the LCMS' historical curriculum.
When something like that gets swept under the carpet, the carpet gets lumpy and loses credibility.
That’s the hazard of having people involved. It’s not just the Lutherans who have a lumpy carpet, to be fair. Pick the confession of your choice, and I’m sure there are as many skeletons in its collective closet that aren’t openly taught.