The author is wrong.
We possess fundamental rights to things such as life, liberty, and property because these things are intimately connected with our self-ownership. As Locke helpfully explains, we own property in external objects because we own our free actions of appropriating them, and we own our free actions because we own ourselves. For Locke—as well as for the American founders and Lincoln—this was as far as our fundamental rights went.
It was from this philosophical lineage that the language of fundamental, natural, or human rights derived its enormous power in political discourse. People have always had intense desires for their lives, liberties, and property—but now these bare desires put on the robes of natural justice and eternal decree. Because of this, fundamental rights are inalienable and non-negotiable; they don’t enter into political discussions, they dictate public policy. According to Locke, their protection is not just one of many important considerations for government—it is the very purpose of any legitimate government. Governments don’t create these rights, they find them already there. Fundamental rights are the “trump cards” of moral and political discourse, foreclosing further debate and discussion.
Marriage is a good thing; both sides of current debates seem to agree on this. But does anyone have a fundamental right to it? To understand why no one—heterosexual, homosexual, or otherwise—has a right to marriage, let’s look again at the list I provided above of good things no one has a right to.
The last two—tropical beaches and lollipops—might in fact be the objects of someone’s fundamental right if one happens to have a legitimate property claim to them. The first, however—world peace—is not the sort of thing any individual can have a fundamental right to, simply because it doesn’t pertain to any individual at all. Peace is something that exists between individuals, not within or attached to any of them. Claiming a right to peace is a straightforward category mistake, like stating that the color blue is five feet long.
Marriage is exactly like peace in this regard: it pertains to a relationship between individuals rather than to any individual in particular.The author is confused on more than one count. One of the reasons that "property" did not make it into Jefferson's Declaration of Independence is because (presumably following Hutcheson and not Locke) Jefferson understood that property is (in the ordinary sense) alienable--it can be transferred, and with it, so can one's right to it. It is therefore not in the same category as life, liberty, and happiness. Not all of the Founders went with Locke in thinking that a right to property is fundamental (and Locke himself thinks that most property is alienable and that in some sense life and liberty are more fundamental than property.)
The author runs roughshod on some very basic distinctions. Here is another one: the difference between a negative right and a positive right. A negative right is a legitimate claim against others to be permitted to do certain things and not have things done to you. Almost all property rights are negative rights. If I have a right to my house, it is a right against your taking it or entering it without my permission. Having a right to life is not a right to have some thing, life, which one doesn't already have; it is a right I have against others to their killing me. Almost all of our fundamental rights are negative rights. In contrast, a positive right is a legitimate claim against others to their giving you things or treating you in certain ways. If there is a natural right to very basic healthcare, then everyone has a duty to provide one with very basic healthcare. We have very few positive, natural (moral) rights. (Well, according to good sense; Democrats, e.g., in today's day will demur claiming a panoply of positive rights for about everything imaginable, including a right to lengthy, paid vacations.)
A right to marry, if there is such a right, is presumably a negative right. If one has a right to marry, then others have a duty not to prevent one from getting married. And surely there is a fundamental right to marry in this sense when one reaches a level of maturity (biological and otherwise). One has a moral right against others to their preventing one from getting married. Whether this moral right is a constitutional right (a species of a legal right) is another question.
The reason that there is no such positive or negative rights to homosexual marriage is simply because there is no such thing. It's like the "right to marry your pet," "the right to marry yourself," or the "right to own a unicorn."