So, I've shipped a game with his engine, so have a unique relation ship with him, and he's a complicated individual.

To be clear, he is a very talented, intelligent individual. But he form strong opinions, has a very hard time taking criticism, or understanding other people's differing context, and has a hard time not taking disagreements personally.

This is really nothing new from him. I think the best way to interact with him, is hear out his points, and use them to synthesize your own viewpoint. And be careful to take his views as your own. I think if you do that, you can learn a lot from him, but to be careful as his strong disagreements are often more nuanced then he makes them out to be.