The funny thing is that those words somehow have actual meaning. Metaphysics is the philosophy of existance. I believe the "true" metaphysics he refers to is the fact that it is unknowable if anything other then you exists, because there is no guarantee you are not a bozmian brain or living in a simulation along other things.

This ability combined with rationality can allow you to adapt to changes in your perception of reality, while other frameworks can't (for example there are still people who don't believe in evolution because there interpretation of god is dependent on god creating all species at the start)