This is the position of libertarians (generally extreme secularist cultural liberals) who don't have the guts to say they want sodomite marriage.
Marriage is a contract between two people and society. A contract between two people is just in a lawyer's office. A marriage is and has always been a very expensive public ceremony surrounded by elaborate ritual. Society no longer has the power to use tradition, family, religion, or fear of ostracism to protect marriage, to protect wives and children from the vagaries of male hormones and mid life crises so it employs the state to do so.
These days, a marriage contract is a far weaker legal instrument than any other contract. A marriage contract can be dissolved by either party for any or no reason. No lawyer would let a business sign such a meaningless contract.
I've never seen this point of view published or heard it spoken. Do you have a URL?
Oral sex is sodomy. Do you object to heterosexual oral sex (sodomy) within a state-sanctioned marriage?