When someone transitions you should refer to them by their new name both in the present and with references back in time.
A quick comeback is usually meant as license to be mean.
I know many of my female friends do not like being referred to as "ladies."
Calling a trans person by their former name is referred to as "deadnaming" and is considered highly offensive to most trans people I know.
Please Mr. Trump: Say what you mean. Mean what you say.
Putting our heads in the sand is not a wise strategy.