They can do anything they want but it is physically impossible for them to be married because they can not consummate their union. There is no argument to that FACT. You can pretend, deflect, spin or what ever, but you can't change that fact.
Gay people can't have sex? So what the hell are they getting all naked for then?
Sex is the biological function of reproduction. It is why our brains are hardwired to mount and thrust. Doing this with the same gender means there's something mentally wrong with you; if you insist on calling it "sex". What it is properly is assisted masturbation.
In any event, it has nothing to do with procreation, which is part of the argument for Utah's vested interest in creating incentives via the
privelege of marriage to encourage people who are having sex [instead of assisted masturbation that will never result in children] to marry. Utah's argument is that they want the acme of coupling to be those people who have the potential to produce children and who present the simplest family unit for maximum care to those children. Just two people, and those two people being man and wife, insures a deep biological instinct to protect that child. And they promote a limited number of offspring inasmuch as one woman can only bear so many children. If you consider that with each new birth in a nuclear family unit, the attention and care each individual child gets is stretched thinner, polygamy decreases that to a transparent thread. Not to mention that a single man in this day and age cannot by himself provide for all those mouths, healthcare and education if we are talking polygamy.
Utah is stating marriage is about the child's welfare and the state's welfare over time and population, balanced. Utah finds by consensus that the best arrangement for this is one man and one woman.
These couples don't always have to produce children. But barren hetero couples do not present a legal problem of the slippery slope. Whereas LGBT situations do. And that slope slides away from a good steady population maintenance and the welfare of children. If gays want to pitch that they as a social group [for ample scientific evidence exists from the most prestigious institutions that aberrent non-child producing sexual orientations are learned] make good parents too, I would bring up the Harvey Milk problem. When 60 + groups of "LGBT" [what is that anyway?...really?] petition for a US postage stamp of Harvey Milk with rainbow "USA" on it, he has become iconic to that behavioral group. The trouble is that
his biography states he was into raping teen boys on drugs.
Since in spite of that knowledge, LGBT groups do not denounce him and instead defend him, society is forced to examine LGBTs value system under and through the Harvey Milk filter.
So Utah properly should weigh, if push comes to shove, whether or not this new religion belongs around children
at all; let alone marrying and gaining a perk of access to adoptable orphans..the most vulnerable citizens of all with no voice at the voting booth and no parents to protect them except the state and the laws it makes and enforces....
Bear in mind that marriage IS a privelege because currently as Utah law is written, gays, polygamists, minors and incestuous couplings are ALL banned from marriage there. Gays are in no way shape or form singled out for discrimination. Though the Harvey Milk situation begs that they should be, and for good cause. Utah discriminates against quite a few people who want to marry there. So either marriage is a free for all the children more and more will suffer though, or there are standards Utah gets to pick to insure the best welfare of each child raised there.