However, those protons are not stable. Their concentration is the result of the equilibrium between neutrons that decay into proton and electron pairs and prot

However, those protons are not stable. Their concentration is the result of the equilibrium between neutrons that decay into proton and electron pairs and proton-electron pairs that recombine into neutrons. The complete neutron star still behaves like a giant nucleus with null electric charge, i.e. with Z=0.