The problem, as alluded by the article, is that too often those arguing against same-sex parents try to argue that it's simply a matter of having two sexes, rather than admitting that the ideal situation is biological parents. The problem being that once you admit that biological parents are the best for the children, you have to admit that all the special acts taken by people to have kids (surrogates, adoption, fostering, sperm donations) are less desirable from the child's point of view. Sure, being adopted is better than being an orphan, but it's not as good as having your biological parents raise you. Biology matters -- that's why so many adopted kids try to find their biological parents.
Is there data suggesting “the ideal situation is biological parents,” or are you arguing from a gut feeling?
I suspect outcomes data would show the opposite of what you suggest. 100% of adopted children are wanted, this is far from the case for biological children.