This idea that everyone either supports full marriage or nothing at all is ridiculous.
Well, the frame of the debate has advanced to the point where these are the two fundamental positions; as you can observe, the fact that anti-marriage people continue to have to moderate their position (maybe in favor of EDNA, probably in favor of civil unions) indicates just how much ground they have lost. Now, while
you might consider yourself a noble exception, a stalwart for civil unions regardless of the political climate, perhaps; in the wider reality of this debate, if your opinion were of any political consequence at all, you would be squarely in the camp of the evangelical movement doing whatever it can to halt the continuation of marriage equality across the country. Indeed, the way you present some of your arguments on this issue hardly does much to dispel that this is the essence of your philosophical motivations.
Put yourself in the shoes of someone who is more directly affected by this policy change. It is now the norm that marriage equality would be tolerated and accepted; for you to say that, no, these rights must be
rolled back, you may as well support "nothing at all." Does that make it a little bit more clear?