The fifth ammendment was just one example. There are other privileges given by marriage that are not covered by civil unions, living wills and other contracts. Furthermore, you are assuming that anyone who invokes the fifth is a criminal, bringing into question whether it should be an ammendment. Also, appeals to tradition are a logical fallacy. Plenty of things were done for a long time and were later acknowledged to be unjust.
Oh, so you put the tradition of marriage in the same category as things determined later to be unjust, like slavery?
Dude, you are reaching. You don't throw the majority to the wolves for the benefit of the minority. I know liberals are oh-so-proud of what they are willing to sacrifice (or require others to sacrifice)for esoteric principles, but that is a suicidal tendency.
And yes, your argument was about protecting gay criminals.
Appeals to tradition are not a fallacy. Marriage has existed for a long time and has a long tradition, and most people feel strongly about it. Those who want to destroy tradition bear the burden of proving that it is unjust, and "feelings" have nothing to do with proof.
You and I both know that gays are pushing for marriage for validation. We (US society) have no obligation to validate what we consider wrong, and certainly not by damaging the institution of marriage any more than feminists and gays have already done.
Homosexuals are people unable to have normal relationships, by definition. Society is not required to bend over backwards for devients. The fact that we do so much of it now portends poorly for the survival of our nation.