Maybe a better explanation is trans people (not transtrenders, real trans people) are less likely to be social butterflies because of the inherent stigma of being trans. Gaming is usually a solo activity. It attracts introverts and other people who aren't extroverted for whatever reason. And "social" interactions on the internet (forums, social media) attract the same crowds, too.
So it makes sense to me that trans people would be over-represented online. They control their persona and image online in ways they can't in real life, and they can really find and communicate with other trans people, who are scattered around the world.
And when they find a hugbox like NeoGAF where the loudest voices (pretend to?) fetishize and celebrate trannies, the most unstable of them probably flock to it