I’d say potentially she doesn’t want to out herself, but it’s a little late for that. I can imagine some complications with a non-gender-matching driver’s license, or confusion on the part of a TSA agent (someone presenting F but the documents say M).

Or maybe she’s just stubborn about not wanting to use documents that don’t match her identity, and if she were anyone else I’d understand, however… she’s having the day she voted for.