All these impersonators are just annoying. It's becoming more offensive that they impersonate so badly than them actually doing it. Not saying that them doing it is better, but seriously, this guy didn't even know your gender, your sibling's gender, didn't even speak like you, and just got your whole entire identity wrong.
These people are really just unintelligent 6 year olds who have no life and try to make other people's lives worse to make up for it.
I'm sorry that this happened to you, and I'm glad that you're back in time to see the impersonation. I know how it feels to be impersonated, only when I got impersonated, some people actually believed it, and it felt worse to know that. But still, it sucks, and I'm here if you need to talk about it :)
-Nobi