Perhaps she will perhaps she won’t. If she does she can tell anyone questioning her she is a woman. She is rare in looking so like a man that no one would know. Usually people would.
If she continues to use the men’s , no one will know anyway according to what you say.
That one person you are acquainted with though does not change the whole principle that goes across so many aspects when sex means sex.
She can get maternity leave if she gets pregnant for example.
She would be doing something horribly wrong if she were to trick a gay man as another.
She cannot lie and say she is her child’s father should she have a child.
I admire those women in Romania ( Look up Last Virgins) who lived as men and looked like men but never pretended they actually were.