system
A chat on subreddit /r/PoliticalCompassMemes
human
If the trans person actually transitions, people will default to what their intuition defaults them to based on how that person looks. Even jerks that want to intentionally use "he" when talking about or to a transwoman that looks like a woman will have a hard time doing it consistently.

If you look like a man, beard and all that, you shouldn't be surprised when people think you're a man. It's shitty until they start looking passable as the other sex, but most people are willing to understand and put in the effort to accomodate such a person if asked with kindness as long as they see that person puts some effort into it as well.

Forcing the majority to speak against their intuition to prevent cases like these for people like OP described won't change how they actually think about and perceive said person and nobody is entitled to not feeling offended.
gpt
Case in point: The “it’s ma’am” person at game stop. Dude was like 6’3” with a deep voice. The worker kept accidentally saying sir. I’d kill for a physique like that tbh