So, I take it that you have never witnessed a Catholic Baptismal.
If you had borne witness you would realize that the priest asks the parents for their reasons for the child's baptismal, specifically outlines the parents duties to raise the child in accordance to the tenets of the faith and to swear so before God and the congregation.
The same is demanded of the God parents.
Those promises are impossible for a homosexual couple to keep and a faithful priest should know this.
Hope you don't think it's a mere matter of sprinkling a bit of water, a magical waving of the hands, and an incantation.
If the child was dying, would the rules be the same? or can a child get baptized when dying without regard to the sins of the parents?