In "Beables for quantum field theory", John Bell has presented a realistic interpretation of any fermionic quantum field theory, along the pilot-wave ideas. This model is formulated on a spatial lattice (discrete space), but he had suspected that the theory could become deterministic in the continuum limit (where the lattice spacing goes to zero).
My question is why he hasn't considered the possibility for the theory to be deterministic on a discrete space lattice, that is, why he has thought that the QFT might be deterministic only in the continuum limit. What prevents the theory from being deterministic in a discrete space?