"All of the sexual prohibitions in Leviticus, including the prohibition against male homosexuality, are rules for effectively upholding the dominance of a real patriarch, the senior father in a tribe of fathers and sons. The controlling of male sexuality in the interests of male dominance- whom men can fuck, when, and how- is the essential in tribal societies in which authority is exclusively male..... The heinous crime is not in the sexual act committed per se; it is certainly not in any abuse of women per se. The heinous crime is in committing a sexual act that will exacerbate male sexual conflict and provoke permanently damaging sexual antagonism in the tribe among men.... The subordination of women was a means to male social cohesion."
- Andrea Dworkin, Right-Wing Women (128).
And herein lies an explanation as to why so many anti-gays are much more outraged and disgusted by sex between two men than they are by sex between two women.
To those who oppose homosexuality on the basis of male and female "complementarism," sex is an interaction between two people a man and a woman, who have an inherent hierarchical relationship to one another. What two "subordinate" (female) types of humans do with one another is not nearly as threatening to this order as what two "dominator" (male) types of humans do together.
Or, as David Benkof, who is also an Orthodox Jew, opponent of same-sex marriage, and self-described bisexual, explains, in Judaism:
"Unlike men, women have no requirement to marry or have children....As far as I understand it, it is not against halacha for a Jewish woman to love another woman, live with another woman, and even share the same bed with another woman. While it is no doubt deeply disappointing to you as parents that she has not chosen to marry a Jewish man and have children with him, it is a legitimate Jewish choice."
A man, you understand, must marry a woman in order to preserve male dominance. What two women do, not so important.