I know very, very few girls who fit the description of pity-mongers, so I don't see how his sexuality really applies. A gay man can be moody just because he wants to be moody, not because he's gay. Some people are just naturally abrasive, and tend to feel like the butt of jokes. It happens, but still doesn't mean he's seeking "special" treatment because he is gay.
If it's something that truly concerns you, more than just a general annoyance, discuss it with him. Clearly, it isn't getting any better at this rate. Talk to him and see why he acts the way he does before assuming he's looking for hand-outs over his sexuality.
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