There are many reasoned arguments to be made in favor of the states recognizing gay marriage.
For example: expanding the definition in no way dilutes or degrades or in any other way harms existing marriages, or threatens heterosexual marriage.
Or: expanding the scope of marriage means there is a significant chance that the institution itself — currently in decline — will be strengthened.
Or: it would help society in general by encouraging more couples to form pair bonds and stable, solid relationships and family units.
Or: it would help bring gay and straight people closer together. Or many, many more arguments, too numerous to mention here.
There are also many irrational arguments to be made in favor of gay marriage. And just as many irrational arguers trying to make their case in the worst way possible.
Such as this tactic.
There’s an old saying: you catch more flies with honey than vinegar. . .