To be clear, I object to both comparisons-- both to the population-wide demographics and the law-wide one -- though I do clearly think it's a conversation worth having.
Because it fundamentally misunderstands what the purpose of representation is. Representation is not an ends on itself, so "matching" population demographics is useless for anything other than identifying likely discrimination. It's not a numbers game. There's no "but hey, look how close we truly are to achieving good representation!" It's not that, because it's still remarkable that this many queer people have been put into power. They're the exception to prove the rule that the field is still inherently hostile to them.
The goal isn't "equal" or "proportional" representation or anything like that. The goal is elimination of the systemic discrimination. The goal is ensuring that brilliant new minds aren't being filtered out for being different from the social norms. This is back to the old RGB quote.