The ΔΦ Neutrino–Antineutrino Symmetry Law v2.0 introduces a theoretical field-structural model in which neutrinos and antineutrinos function as complementary coherence regulators within a ΔΦ-based cosmological substrate. Building on prior ΔΦ frameworks—including electrosensory ΔΦ navigation, ΔΦ instability geometry, ΔΦ Coherence Cascades, and ΔΦ Genesis Cosmology—this manuscript proposes that neutrinos behave analogously to the forward-propagating signal of a macro-neuron, while antineutrinos serve as the cosmological refractory phase enabling reset, stabilization, and preservation of large-scale coherence. The law defines a formal relationship between divergence-driven ΔΦ field activity, quasi-neuronal cosmic propagation, and systemic re-equilibration. This work is presented as a purely theoretical component of ΔΦ field cosmology and does not assert empirical claims beyond prior published ΔΦ manuscripts. No biomedical, clinical, or intervention-related interpretations are made or implied. The resulting model positions neutrino–antineutrino symmetry as a foundational mechanism in cosmic timing, coherence retention, field reset behavior, and the emergence of persistent large-scale structure. This manuscript stands as an independent theoretical contribution within the broader ΔΦ scientific corpus.