Don't use to support an argument though. Luffy is very responsive with his comments. He was told that Yamato wanted to be Oden, so he called her Yamao. It's even treated as joke in the manga.
Plus, when Yamato is is introduced, the narration says Daughter, not Son. I know there is a huge gender argument about it, but I don't want to be involved.
People need to wait and see if Yamato continues to call themselves Oden and a man. If that's the case, then it should be respected. If not, then it doesn't matter. All sides are jumping on this without fully understanding context.