He was trash talking Tesla for a long time because his friend Warren Buffet invested in Chinese copy cats. He could have helped Tesla in 2008 a lot, but now his opinion and money doesn't count that much actually, as there's a healthy clean energy investor base at this point.
I wonder if he cashed that out in recent days now that his short position is in the money? If so then maybe he doubled (or better) his $500M and he can plow those profits into more philanthropy?