Mmm while I can understand an innocent mistake and many people WILL forgive these things, you need to think of these in a greater context: you misgender someone one day, and it was not intentional or malicious, but it happened. And it hurts. This person is probably misgendered often, multiple times in the same day - they have difficulty knowing with bathroom to use, in part because of concern for their own safety. People likely intentionally misgender them as well, tell them they are NOt the gender they are, sa because they have x body part they MUST be this, insult their appearance, trans people risk VIOLENCE for being who we are, when people even let us exist.
No, one accidental misgendering may be an innocent mistake, but is CAN hurt and even be dangerous in the wider scope of things.
And no, we don't need the conflict, but why should someone have to be misgendered to avoid it? Why can't others just not assume gender, or ask, or use neutral pronouns if unsure?
And while that's a good stance, there's more than "two genders" so there isn't really an opposite gender. Everyone should be called by the pronouns they like, and that is that.