Adoption.com is a "private business" selling a product, babies for adoption, at a certain price, for a profit.
What is the constitutional basis that any government can dictate what price a product can be sold for and to whom the product is going to be sold to?
Free people, when espousing liberty, necessitates and demands that only the "private business" or property owner is to make that decision.
The right to discriminate, for whatever reason, is as basic and inherent as free speech, see Supreme Court Gilleo v City of Ladue.
So you are saying that molesters can buy children and the government should be unable to interfere?
Yikes!!