That's a common misconception. In fact, he wasn't a vegetarian though he rarely ate meat.

He had some very strange dietary habits partly due to a persistent stomach condition and partly due to his drug use. He experimented with strict veganism at one point in an attempt to sort out his stomach, which I believe is probably the root of the "Hitler was a vegetarian" rumour, but it didn't cure him so he dropped it after a while.

As I say though, he did have a diet that was close to vegetarianism (apparently mashed potatoes were his main thing) but otherwise it's a myth.

I agree with the rest of your post though.