Why revisionists might pause to acknowledge conservative concerns

My letter posted below concerning Archdeacon Glynn Cardy's open letter re the blessing of same sex partnerships has led to a challenge to me to consider the danger of emphasising the law over the love for one another which Christ taught and modelled. That's quite fair. The law is always about people, and for Christians people are never mere case studies in the advancement of the law. The law is to serve people in the name of the God of love.

Yet I do not resile from seeking to secure (if possible with my brain of a small size) clarity on matters of theology and canon law through rational discourse, impersonal though that may be. In the end the love of God and our understanding of it is deepened and widened through foundation in the truth rather than wishful thinking.

One concern which conservatives make (noted in a comment on a post below, but also in many other posts across the internet) is that the church formally giving ground to the claims for formal blessing of same sex partnerships opens the door to moral incoherency. The ability of the church, for example, to sustain a scriptural argument against polyamory or incest, would be weakened severely, if not disabled permanently, is something we worry about.

I simply do not know what revisionists of traditional moral positions have to say about these concerns. But I would like to know, because these concerns are not abstractions from real human lives. In the Christchurch Press today (Saturday, July 19, page B4) an article is carried with this heading: 'I had sex with my brother but I don't feel guilty.' It was sourced from The Times (London) and you can read it here (warning: some detail may offend). Quite why the Press or the Times is carrying such an article I have no idea (other than the obvious one of selling a few more copies). But I am tempted to think about secular humanist conspiracies ...!!

That is, (a) incest is a fact in Western society (b) it is not obviously wrong to some who commit it (c) major cultural influences (the media) are prepared to print a substantive testimony in favour of the hypothesis that incest is not wrong. What do revisionists have to say? Is it not wrong? Is it right in some circumstances? If it is wrong, why?