Those numbers are wrong for many reasons.
First, a lot of people are in the closet, especially in countries where there’s death penalty for being openly gay.
Second of all, “straight” or “gay” are just terms. People can say they identify as straight, gay, bi or something else, but it’s more complex than that for other people. Those are just labels, maybe someone who considers themselves as straight can happen to find a special someone that can make them reconsider how they feel about other people (maybe it’s Soldier’s case in the lore).
Maybe no one is really gay or straight but we feel like we must be part of a certain “box” to feel good about ourselves. If no one really cared about “labels”, we would be free spirits without asking about one’s sexuality. Why does it matter anyways ?
Live your life, feel free to love whoever you want (as long as it’s consented and between adults). Everything could be so easy but we spoil everything in this society by judging the most irrelevant things.
And about your 96% straight people, who knows how many people with illegal sexualities like sex criminals or children abusers are hidden (same goes for your 4% only LGBT people). I think there are many people who belong in that category and that never actually harm others and control themselves (others do harm people and end up in jail).
The world is not that simple and I don’t think there’s that many “pure” straight people as you might think. One mind is so hard to decipher. We all have many secrets because some of them might make us look unaccepted or as outcasts to others.
Edit : stereotypes can touch anyone, whether you come from a minority or a majority group of people.