I would call Joss Whedon a fan-boy and would say that he has a comic-book sensibility, but he does know camp. Being able to incorporate camp into his work does not make him a gay artist, no matter that some of his shows greatly appealed to a gay audience.
From an article in backstage by Erik Haagensen – June 2003, Craig Lucas likens "gay sensibility" to a tautology . . . "Every artist has an individual sensibility that they infuse their work with. If an artist is gay, then the work has a gay sensibility."
I would have to agree with Mr. Lucas, his observation is hard to refute. A work of art created by a gay artist would necessarily involve their perception and understanding of the world. And a gay person's viewpoint is not the same as that of a straight person—having said that, it doesn't automatically imply that anyone would detect, or need to, any of the differences in a work of art.
So, to answer, I think the greater context is better established by subject matter than any "gay sensibility".
And a Happy Birthday to you, hh5.