My goodness how much ignorance from the guy from duke, later interviewed. True analog computation, aka real number or infinite precision computation, does not exist in the physical world. The other possibility Quantum computation, is not believed to occur in the brain. While there are gradients across membranes, that are 'pseudo-analog', for all practical purposes they are not true analog, they are discrete, digital in nature.
As for Musk, one of the worries about true AI is if it can be made to operate in a virtual environment hundreds, thousands or perhaps millions of faster than human thought and conversation. There is no interfacing or meaningful way to interact or keep up if that becomes possible, you need a complete re-engineering of the brain at a fundamental level.
Also, if you've seen neurosurgeons poking around you should know that with a high enough quality interface to the brain you can affect desires, emotions, thoughts, even the very will itself. The person becomes a complete puppet, you control even what they want, even what they decide.
This is no, oh the person is resisting, there are areas where you activate and the person says they didn't make the movement you made it, but there are others were they believe they actually chose to make the movements being made by external stimulation. Their very want can also be changed, what they actually want changed to whatever is desired.
Brain machine interfaces are the key to ultimate freedom from the physical limits of reality, but they are also the key to the ultimate enslavement, where everything lay bare, thought, feeling, emotion, memory, desires and everything is open to control based on your whims.