You’ve probably heard that Ohio ultra-conservative Senator Rob Portman has changed his position and now supports same-gender marriage—because, he says, his son is gay.

That’s great for progressives. But…

Wanting equal rights for your son is a poor reason to support equal rights for a class of people. It reflects exactly the kind of tribalism that’s preventing most of the Arab world and Africa from creating secular democracies. In Iraq and Afghanistan, for example, "voting" is simple: Sunnis vote for Sunnis, Shia for Shia, Kurds for Kurds, and so on. This isn’t voting—it’s tribal warfare brought indoors.

There are still no civic institutions knitting together the countries of Iraq or Afghanistan, or of Syria, Lebanon, Albania, Rwanda, Azerbaijan, and other places where ethnicity and family history are more important than national identity.

Senator Portman sees public policy as a way of comforting his family, not of nourishing the American people. His statements this week showed no recognition of any actual principle of fairness. He acknowledges that his past opposition to civil rights for gay people is rooted in his faith tradition—itself a bizarre, if too-common, abdication of his legislative responsibility. He now says he sees gay couples’ desire to marry as a tribute to marriage rather than a threat, recalling the old fear that giving Blacks civil rights would endanger the rights of Whites. He also says his new position is rooted in the Biblical value of compassion.

But as inappropriate as it is to reference his nouveau interpretation of the Bible for a legislative position, he isn’t extending this “compassion” to any other Americans in any other situations.

So this is a mind that has not opened. Because, as Portman himself said, he’s "had a change of heart based upon a personal experience”—not social science, not Constitutional analysis, not a desire to extend America’s promises to all its inhabitants.

In order to implement this Biblical “compassion” among the rest of his eleven million non-gay constituents, does Portman require a daughter who needs an abortion, a son who marries outside his race, a grandchild with a mental illness, or an elderly parent who can’t afford medical care? For the good of the nation, should we hope that Portman’s brother is swept up in an FBI sting while enjoying age-play fantasies in an adult chat room?

Our government confers dozens of civil rights on everyone who marries. Thus, all adults should be eligible to marry, or the government should stop privileging married people and simply go out of the marriage business.

So I’m glad to have Portman’s support for extending the option of marriage to non-heterosexual Americans. But this support is just a kinder, gentler version of political opportunism. Instead of voting in a way that lines his pocket, he’s now voting to enrich his son’s life. Other gay men and women will benefit. But anyone else who needs “compassion”—or as I call it, civil rights—will have to wait until the next development in Portman’s private life.

Dr. Marty Klein has been a sex educator for 30 years. He is the author of America’s War on Sex: The Attack on Law, Lust, and Liberty and blogs for Sexual Intelligence. This article first appeared on the author’s blog, which has been edited for content.