Tough call, between the idea that government should stay out of personal business and the idea that our society benefits from the traditional marriage. Both good ideas, but traditional marriage is on the skids as far as the way government handles it.
If anything, it should be up to the states, not the feds.
I don’t think you can count on the government to protect the marriage from homosexual unions, the government will ultimately approve marriage between anybody and anything. That is something the churches should be doing.
The two ideas are not necessarily in opposition. Society benefits from many things that don't get special state recognition.
If a man and a woman want to live as husband and wife they don't need a special government license to do so. If they are concerned about division of property and the like they can enter into contractual agreements with each other before marrying at the church.