I don't know if it's helpful OR productive to construct a narrative around the situation. I don't know who came up with military, but that seems unlikely. You ever hear the saying that the obvious answer is usually the right one?
She's a transgender woman who was called "sir." The obvious answer is usually the right one. Looking at her, there's no way he didn't know she identified as female. So he probably said it to be a jerk. Judging by all her "y'alls" I'd say she lives in the South.
I can say that living in the South was BRUTAL on my early transition. We all go through our phases and have our off days. For me it used to be one minute a guy would say I was the hottest girl he'd ever seen...than I'd here "are you a guy?"
I feel as though FFS has already dramatically improved my overall presentation...so Angelique, it may be better to look into that. But please don't bury your head in the sand. It makes things WORSE emotionally when it becomes impossible to make excuses and it makes you less vigilant—which can be dangerousz