Some trans women are as you describe, preoccupied with passing and going stealth, especially for safety reasons. Many aren't.
You can speculate on if the term is gonna go away, but right now it's the best adjective to describe trans people. It's not offensive or a slur, it's literally the community's chosen language.
And you're right, sometimes it's better to be nice and gentle to people who are wrong. I won't be mad if you pop back upthread and correct them gently. We can do one of those good cop bad cop things.