You would think you'd want to protect your intellectual property when you're building complicated things like spaceships and innovating new technologies daily.
But Musk's decision actually makes total sense. Why is that? Musk explains in a recent interview with Chris Anderson at Wired:
Thus, Musk's only option is to go with the trade secret route. That should end up working for a company like SpaceX, but as patent fights ramp up, something has to be done.