His arguments are based on the assumption of "we are biological computers made out of atoms flying in spacetime".

Authors of this conference argue precisely against this assumption - e.g. they explore alternatives in the "beyond physicalism" book.

He claims that we figured all the physics relevant for the brain, so there is nothing potentially there. Penrose and Hammerhof theory of quantum processing inside the neuron is still under heavy debate. We still weren't able to simulate a single biological neuron - see blue brain project. Donald Hoffman presents solid arguments that spacetime and "atoms" are projections from some more complex reality underneath.