I printed the whole damn thing out, all ten pages, and tried to read it. I gave up at page nine. The incoherence is just staggering. I'd rather try to understand the Copenhagen Interpretation of Quantum Phenomena. So, while I can't claim to understand the entire argument (and I really do not want to, either), I think I sorta understand the author's justification for the legal recognition of same-sex "marriage". He argues that the purpose of marriage that applies to all couples, fertile and infertile alike, is the promotion of sexual fidelity. Since same-sex couples can practice sexual fidelity, same-sex "marriage" should be legally recognized.
This is just bullshit. And I say this not because I think fidelity is impossible within a same-sex relationship. I say this because sex is impossible within a same-sex relationship. Sex is an abbreviation for sexual intercourse. Intercourse simply means communication or interaction. Human intercourse means human interaction, bovine intercourse interaction among cows, and so on. Thus, sexual intercourse must mean interaction among those things that are sexually distinctive. A hand is not sexually distinctive, neither is the mouth or anus. "Same-sex sex" is impossible because sexual difference is the sine qua non for sex. If same-sex couples cannot have sex, they cannot practice sexual fidelity.
Now one could re-define 'sex' as anything involving two people that may lead to orgasm. The New Hampshire Supreme Court contemplated doing just that, and the Liberal Majority (the Conservatives dissented) decided against it, explaining that such a re-definition would be so subjective as to be legally incoherent and, hence, unactionable. The case was Blanchflower v. Blanchflower, and the winning plaintiff in that case was none other than a Lesbian!