When you think about it, yeah, maybe he is.
Let's break it down.
Yes, he's crazy and he tried to send the world into chaos.
Yes, he's a murderer.
But when you get down to it, he's follow a lot of.... Airbending philosophy.
I mean, he learned how to fly! How to fly! Aang never learned how to fly, neither did Tenzin!
Even Tenzin said he's using techniques that haven't been used in thousands of years.
He reach spiritual enlightenment, left behind his worldly possessions and could even enter the spirit world at will.
Maybe, the reason why he almost killed Tenzin is because he's better at Airbending than anyone who came before him, including Tenzin.