It rests on two rather vacuous assumptions: First, that at present there exists a wide spread belief that homosexuals are hypersexual, infidelious and promiscuous, and second, that this is, in no small part, due to their not being able to marry.
The same-sex marriage debate is fundamentally a normative ethical one. Same-sex marriage is not a civil right because, simply, homosexuality is not a civil right. But when one group gets access to both civil unions and marriagebut another group only gets access to one just the civil union, sorrywe have seen no evidence of legitimate justification for governments essentially segregating access to rights and full-incorporation of minority citizens.
Lastly, the impact upon those individuals who oppose same-sex marriage, or homosexuality as a whole.
Yes, related issues, such as the right to not be dismissed at work or ill-treated at work, on the basis of your orientation, constitute clear cases of human rights abuses. Mandating gender-difference for marriage creates significant problems for these people. This rebuttal effectively argues that the state must act as a pathfinder for society, leading the way for its citizenry.
This argument, which was justified by analogy only and no actual analysis of the example of marriage , was dismantled rather thoroughly by team opposition. The Supreme Court itself has powerfully contributed to, and in a sense even required, this sort of rhetoric of demonization.
Homosexual civil marriage would make it even easier than it already is for men to rationalize their abandonment of their children.