This is the best argument you have against SSM?
This is one of many;
The differences between marriage with/without kids and gay couples;
A apple tree bearing fruit.
A apple tree not bearing fruit for some reason.
A walnut tree who never bears any fruit wanting to be a apple tree.
A walnut tree hanging apples on it's branches pretending to be a apple tree.
The claim that if the government doesn't 'require' apple trees to bear fruit, then it is discrimination not to call walnut trees apple trees too is simply silly.
Marriage is a cross cultural constraint on evolutionary mating behavior.
Gay couples do not just fail in the primary essence of marriage, out of all relationships, they are the oxymoron of marriage.
Moreover, if you remove the element of procreation, you dumb down marriage to just a friendship. Hardly a cause for government interest, let alone selective discrimination.