As far as I know, no recent court has found that there is a rational basis for anti-gay-marriage laws. The Nebraska decision hauled up a 1972 decision, back before much of the science was in. And the entire point of Prop 8 in specific was to strip a right from gay people by amending the CA State Constitution, so I'm going to stand by my assertion that marriage redefinition is not what's going on here. Indeed, it's Prop 8 that explicitly redefined marriage here.