Well, firstly, self-reported LGBTQ percentages are always going to be lower than the actual numbers. I guess 20% is a better proportion than the 2% given above, but I’ve certainly seen suggestions that half of all – or even all – people are at least slightly (subconsciously) bisexual, but in most cases they don’t even realise it. And then there are biromantic people, who would be fine with a romantic relationship with anyone, even if they’re not sexually attracted to them.
But that’s not really important. As I’ve said before, what’s “realistic” (or at least what seems to be realistic) isn’t that important, especially for a game. What’s important is ensuring that people (whether they’re LGBTQ or not) enjoy the game. And if there’s only one option for gay players but four for straight players, then it’s not going to be as enjoyable for gay players, and I’d also wonder exactly why the writer thought that having one option for gay players vs four options for straight players would be seen as fair.