I also think that "19 is too late to transition" is the sort of belief that can only gain a toehold in settings where "don't talk to adults/don't talk to older adults" is the norm
"Why are you as a thirty-something talking to a nineteen year old" I don't know, maybe because I don't typically choose my conversations based on the age of the other person? Like, I'll pay attention to people's ages when it's pertinent to not being a creep but otherwise I'm not gonna limit myself purely to social interactions with other thirty-seventh-graders.
Also everyone tends to think of "not being a creep" in terms of sex stuff but to me it also encompasses being mindful of other people's vulnerabilities when you're navigating conflict and disagreement. I had a former friend who had "minors dni" in her bio and yet thought nothing of quote tweeting a teenager to dunk on them. And that's why she's a former friend.
"I'm right so I can say whatever I want to whoever I want" is a mindset you need to divorce yourself from before you start seriously harming people