I'm not sure if Musk's contention makes sense because intelligence isn't a uniform attribute to systems (biological or synthetic). Specifically, what passes for intelligence is just the proper applicable, discovery, and/or refinement of algorithms which we can do easily without intelligence (as in self-awareness and raw analytical capability). Just run through all possible paths or solutions on a sufficiently fast computer and you'll eventually get all the possible solutions to any given problem. It's not a matter of intelligence, it's a matter of lifespan and applicability.