I agree with everything @Riemann has posted in the OP and afterwards. Including that that thread title should have been modded from the start.
You thought wrong about this specific issue (my emphasis):
- Do not deliberately misgender another poster – that is, refer to them by a pronoun or other sex-specific term indicating a gender other than the one they identify as. This applies only in cases where a poster’s gender identity is reasonably clear. Likewise, do not deliberately misgender off-board figures. This is a more rigorous standard than we apply in other contexts; we do not normally mod posters for merely insulting off-board figures. Deal with it.