As an LGBT person, I can see why this is disappointing. Truth is there are so few big gay roles in stuff that yes, from our community's point of view, it would be great to see a gay person getting that role.
I think it's hard for straight people, who see themselves reflected on tv and film every day, being played by people with the same sexuality as them to understand fully why gay people would be disappointed by it.
Is it just me that's sick to the back teeth of these people popping up here with no understanding of the audience and with the intention of explaining the LGBT community's views to what they (clearly, given the 'cis') assume is an exclusively straight, gender-conforming audience with no clue?
There are fucktons of LGBT people on Mumsnet. Not the Tumblr-bubble type, though, perhaps...