= Solution
Increasing $\kappa$ makes $\Gamma_W/H$ smaller at every fixed <temperature>, so freeze-out occurs earlier, at a higher $T$. The equilibrium value $e^{-Q/(k_BT)}$ is then closer to one. Although some neutrons subsequently decay, the final neutron fraction is larger, and
$$
Y_p\simeq\frac{2(n_n/n_p)}{1+n_n/n_p}
$$
increases, approaching unity if the surviving neutron and proton abundances become comparable.
Such a universe begins with less hydrogen and more helium. It has less fuel for long-lived hydrogen-burning stars; stellar evolution would tend to proceed through hotter, faster helium-burning stages, reducing typical stellar lifetimes. The shorter stable-energy window, altered heavy-element production, and lower primordial hydrogen abundance would make familiar water-rich, slowly evolving habitats less likely, although a detailed conclusion would require a stellar-evolution model.
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