Yes, Virginia, it is reasonable to argue Frozen has a gay agenda. Here's why.
The whole point of fairy tales is to tell stories with archetypes whose struggles work on multiple levels and speak to different situations. Elsa's is the story of a girl who was different, whose parents felt she should hide that difference. A girl who felt isolated despite the love around her. On the surface it is the story of hidden power, the fear of an accusation of witchcraft or sorcery. Those are still real concerns today, and to every little pagan kid in the audience, the story touched a chord. For the LGBT audience members, they may have identified with Elsa's isolation too, and that's, wonderful. That's the point.
Elsa began concealing who she was for the sake of other people's opinion and learned that the path of honesty, love, and self acceptance can make the world a better place. Who can't benefit from that lesson? The closet atheist, the creative depressive? No, everyone can benefit from that message. So while yes, there has been a lot of drum beating with the far right, dare I say extremists, decrying that Frozen is nothing but shoring up the Same Sex Marriage argument and normalizing homosexuality, really it is just normalizing vulnerability, inner strength, and the positive effect of embracing our individuality.
Go out there and interpret Frozen. Then reinterpret it. Deconstruct it, compare it, look at the symbols and pick apart the social values. Mock Anna's lack in judgment and scratch your head wondering where the Regent went. Connect with the piece. It is a fairy tale, created for human connection- a metaphoric prism through which we can all view many things, even the "gay agenda." Then when you've exhausted yourself, Let it Go.