I just don't see how that follows. We use randomness to create non-randomness all the time. It's how our muscle and nerve cells work. It's how all our cells work. It's how our immune systems work.

My thoughts are to a large degree created by "non-rational" processes beyond my control. The underlying chemical and electrical processes are not controlled by me. The activities of the individual cells participating in the creation and processing of ideas are not controlled by me. The information that is recevied by my eyes, or ears, or whichever sense organ is not decided by me. All of that is constrained by the physical laws of the universe. "Free will," whatever you decide that means, has to occur with the physical constraints of the universe.

Here's something else: as far as we can tell, we have free will. If that's not the same thing, the difference is meaningless.