For me, personally, the identity of the cast and crew don't really sway my love for Queer movies. Brokeback Mountain, for example, is a movie I adore and I don't know anything about the cast or crew being Queer. Milk's cast, also, is predominantly heterosexual, but I still love that movie with all of my heart. Similarly, I don't think that the Queerness of Heavenly Creatures is detracted from because of the heterosexuality of the cast and crew. Even when movies aren't supposed to be Queer in any way, people sometimes find Queer meanings and relationships. For example: Robert Downey Jr. as Holmes and Jude Law as Watson in the recent Sherlock Holmes adaptations by Guy Ritchie or James McAvoy as Professor X and Michael Fassbender as Magneto in the latest X-Men movie. People find meaning where they want to, regardless of identity. I think the Queer eye of a director is helpful in some cases, but it doesn't make or break a movie. The TV show Glee is directed by Ryan Murphy, who is publicly out as a gay man, yet Glee is full of bi- and transphobia, along with other problematic ideologies and stereotypes. (As far as Female Trouble is concerned, I honestly have no idea why it has such a huge fan base!)
I think the Queer emphasis on Juliet and Pauline's relationship in Heavenly Creatures makes a lot of sense, at least from my perspective. If they hadn't done anything with that relationship throughout the movie, I probably would have assumed it was Queer anyway and would have been perturbed that the movie didn't do anything with it. I also thought it made sense in that the girls reacted so vehemently when they were threatened with separation. Creating an alternate world as an outlet for their relationship seems very plausible, especially with the timeframe they were working with. People do the same thing today: they create identities on the internet in order to experience a life(style) they're too afraid to pursue in reality. The Queering of Juliet and Pauline's relationship made sense psychologically without demonizing the Queer community or painting this picture of lesbians as insane killers.