Clint sums it up in the best way possible.
"These people who are making a big deal about gay marriage? I don't give a fuck about who wants to get married to anybody else!
Honestly, that's the best possible answer. It's not based on any agenda, it's not conciliatory as if you're giving somebody something they don't deserve out of the kindness of your heart, and it's not a begrudging acknowledgement of the subject because you feel like you can't win. It's just a simple, "Who cares what other people do.".
This is Clint's world. He's spoken. Now shut up and get off his goddamn lawn.