I do n;t know that there has been an effort to make it into a movie, Artiste, and I cna't really speak to weather or not the state refused it, as I don't live there. I did read the book, someone recomented it to me on the Proulx website back when they had a forum. It was an interesting read, but it was no Brokeback.
Now as for Brokeback Mountain, Proulx has maintained it is a story about the effects of rural homophobia, but I think the movie made it much more, it carried us beyond that.