Genesis 1:28 and Same-Sex Marriage

I recently had someone quote Genesis 1:28 to me as though it were an argument against gays and lesbians being allowed to marry, since they cannot fulfill what it commands. This is how I replied:

If you are referring to reproduction, then they have the same options available to them that infertile heterosexual couples have. If you are referring to ruling over the fish, I haven’t figured out how to do that yet myself…

Genesis 1:28, in case you don’t know it, reads:

God blessed them and said to them, “Be fruitful and increase in number; fill the earth and subdue it. Rule over the fish in the sea and the birds in the sky and over every living creature that moves on the ground.”