Personally, the sexual identities of the cast and crew of a given film have never been a factor in the credibility I place on the film's interpretation or representation of a story. When it comes to the true story of Heavenly Creatures, I am very satisfied by the fact that the narration comes from Pauline's diary entries and that there were many congruent depictions of the mid- 20th century that surrounded the young women.
I feel that just because someone identifies with a plot-line, or a specific character does not necessarily that they give an accurate depiction of the story. I think it could work in reverse, at times even. However, with the right intentions, a person of any identity can accurately portray any given character and his/her life.
Just as it seems unreasonable that we can disregard all films based on women that are directed by men, I feel it is similarly closed-minded to say that a queer identified person could not accurately create a film of a non-queer identified person/lifestyle.