A large part of Hei Bai's problem was he couldn't communicate with the humans, so there was no possibility of "HOW DARE YOU DESTORY MY FOREST?" "It wasn't us! It was the Fire Nation! Here, let's help you replant it." So he communicated his anger the only way he could -- through violence.

It's definitely an interesting theory - rather like Princess Mononoke, and would tie in nicely with Korra not being very spiritual. His speech didn't make me think of Koh -- it struck me more as poetic emphasis -- but I can see it now, especially with how he reaches for Korra's face in some of the previews. I'd still prefer him being human, but it will be interesting to see how it plays out either way.