As long as 'personal lives' are tied to legal issues such as taxation, it is not a 'personal' or even 'social' issue. Many gay people now get married in private ceremonies that have nothing to do with government recognition. The Unitarian church performs these regularly. It is when they demand that the legal definition of marriage be changed that it is no longer a personal matter. The definition has spanned almost all cultures, religions (it isn't just a 'Bible thing' as many put it) and nationalities. It is a recognized legal definition. The Constitution does give Congress the authority to ensure equal application of legal issues (Article 1, Section 8 to 'define standards for weights and measures', legal definitions used in contracts and laws fall under 'measures'). Coulter is right. The law doesn't prevent gay people from getting married, it just defines who they can marry if it is to be a legally recognized marriage contract. It is blind to if someone is gay or straight. The legal definition is a partnership between two people of the opposite sex, who aren't already married, who are not close relatives, and who have reached a minimum age. That is a uniform definition of that legal term that is recognized almost everywhere.
You are exactly right. Why does Stossel pretend as if Republicans are llcalling for police raids of private gay “commitment ceremonies”? I wouldn’t normally ask, because people will use whatever’s at hand to win an argument, and just like they misuse the equality argument because it’s important in our culture to pretend to believe in it, there’s also still a residue of regard for freedom to which we bow in empty ceremony. But if you can rely on libertarians for anything, it’s to keep clear the division between government intrusion and living your own life. Everyone partakes in special pleading, of course, but this seems too obvious.
Gay marriage is not an equality nor a liberty issue (except, maybe, to people who advocate tearing straight marriage down to equalize it with homosexuality, but then we’re not talking about gay marriage, are we).