I actually like Harari's ideas generally, but this seems like an incredibly silly explanation to me.

Our bodies obviously coincide with sentient perspectives for a reason, and that reason must be that sentience / consciousness has an advantageous physical effect on the body.

To me, the solution is to essentially conflate "consciousness", "will", and "force" as different sides of the same coin.

Our bodies, therefore, incorporate consciousness because it is inherently willful, which is to say, forceful - like gravity or electromagnetism.

And just as we don't think of gravity and electromagnetic force as having "free" will, neither should we think of sentient force as "free". To do so would violate Occam's razor, because it would unnecessarily imply that each person's sentient force was inherently different than everyone else's. Better to assume that everyone's "will" derives from the same universal sentient force.