Of course it's kinda tempting but if I were the guy introducing the tranny I would have just not bothered to announce any title such as Mister. Just let it go.

Any guy dressing in women's clothes, in public, and even actually pretending to be one, well they clearly have serious mental issues and need proper help rather than making a big scene to stress them even more about it.

I know it feels like if you accept him/her/it as an authentic woman then you have been pressured into going along with the fraud, but ultimately it's none of my business how someone else wants to live their life.