Well, according to one person I ended up arguing with, they're part of it too because the A in QUILTBAG only stands for "ally" and nothing else. It meant "ally" before it meant "asexual" or "agender," so saying that it can be any of them is just revisionism. So even if they're straight, they're still part of the LGBTQ+ community too.

At which point I just kind of went "...g'nite, everybody!" and wandered off, because I did not have the reserves left to explain to them the many, many, many things wrong with that idea.