He's saying the lead developer behind PhysX and marketing manager of CUDA is working on Bullet now. He left back at the start of 2010. Either way PhysX isn't using x87 since 3.0, so that argument is irrelevant. 3.0 is a complete rewrite of PhysX from the ground up and afaik has yet to be implemented in a game. Nvidia has a huge advantage in industry support (people who are already implementing and using PhysX) and their SDK is already fully developed. It also helps when they partner up with companies like Epic, whose engine is used in tons of games.