I don't know where you guys got this idea of patent exchange.
To me in 'good faith' means, go ahead and use my technology and if you improve on it, then make that also free and do not lock up improvements or any discoveries you made on top of Tesla's inventions. Just like Open source software
Often Patents are used not necessarily to build great products and make profit out of it, but to essentially block others from advancing their products. Sometime they lock a whole line of technology because the fundamentals are patented. Also the other motive is to sue if in case someone ends up using your patented tech. This is what irks Musk.