With the Nazi party stimulating having blonde hair and blue eyes, how were they able to get away with it by not having it themselves? No-one from the top of the Nazi party (Hitler, Göring, Goebbels, Eichmann, Hess, Himmler, Speer) had blonde hair, I'm unsure whether they had blue eyes.
There's surely someone who knows more about it than me here, but the premise of your question is wrong. People who were blonde and had blue eyes weren't necessarily Aryan and vice-versa, since someone was a member of the Aryan race if they were European and had no Jewish, Slavic, African, or Asian recent ancestors.
Blue eyes and blonde hair were merely considered characteristic of the Aryan race and a symbol of beauty. Look at the Nuremberg Laws if you want to know more about it.