Pete Wehner is offended that his view that his relationship should be worth more than mine under the law because he's heterosexual can be described as "discriminatory." How can it not be discriminatory? You may want to describe your view as merely wanting "to preserve the traditional meaning of marriage," but when that preservation is entirely limited to keeping gays out, and you want the law to enforce such a distinction, then it is simply a fact that discrimination is your policy. You think it's good discrimination, but it's still discrimination unrelated to any civil marital responsibility a gay couple is prepared to fulfill.
This remains true however such a policy is maintained or arrived at - by courts or legislatures or, as is usually the case in the US, some combination thereof. What neither Wehner nor Obama have fully grappled with is that there are really only two coherent positions: civil equality or civil discrimination. Obama wants to end discrimination but not embrace equality; Wehner wants discrimination but not the moral taint of being a bigot. These straddling positions are not unusual in the midst of social change. But we have reached a point at which the useful fictions on which they rest are crumbling.