Is 2 kingdom 2 queer?

When Lee Irons posted Misty's now infamous case for homosexual marriage on his church website, he eventually lost his job over the ensuing firestorm. Now, years later, here's what Horton has to say:

Third, in my own wrestling with the political debate, love of neighbor looms large. Some on the right may offer arguments that reflect more the same demand for special rights as those on the left of the issue. The legal aspects of that are beyond my pay-grade—and they are important. Others may treat this issue as irrelevant: “Look, it doesn’t affect me. I just don’t want to live next door to some creepy home like that.” However, in terms of specifically Christian witness, love of neighbor (as God’s image-bearers) should be front-and-center. We have to care about our non-Christian neighbors (gay or straight) because God cares and calls us to contribute to the common good.

The challenge there is that two Christians who hold the same beliefs about marriage as Christians may appeal to neighbor-love to support or to oppose legalization of same-sex marriage.

On one hand, it may be said that if we can no longer say that “Judeo-Christian” ethics are part of our shared worldview as a republic, then the ban seems arbitrary. Why isn’t there a campaign being waged to ban providing legal benefits to unmarried heterosexual couples? Or to make divorce more difficult? It just seems more symbolic than anything else: it looks like our last-gasp effort to enforce our own private morality on the public. On the other hand, we might argue that every civilization at its height, regardless of religion, has not only privileged marriage of one man and one woman but has outlawed alternative arrangements. Same-sex marriage means adoption, which subjects other human beings to a parental relationship that they did not choose for themselves. Are we loving our LGBT neighbors—or their adopted children—or the wider society of neighbors by accommodating a move that will further destroy the fabric of society?

I take the second view, but I recognize the former as wrestling as much as I’m trying to with the neighbor-love question. Legal benefits (“partnerships”) at least allowed a distinction between a contractual relationship and the covenant of marriage. However, the only improvement that “marriage” brings is social approval—treating homosexaul and heterosexual unions as equal. Although a contractual relationship denies God’s will for human dignity, I could affirm domestic partnerships as a way of protecting people’s legal and economic security.

http://www.whitehorseinn.org/blog/2012/05/11/should-we-oppose-same-sex-marriage/

What's the substantive difference between civil marriage and civil unions/domestic partnerships? Why was Lee (rightly) drummed out of the OPC (although he only lost by one vote) while Horton's compromise position is acceptable?