I'm glad you were able to find another job that actually respected your gender identity. Honestly a company that doesn't respect a person's gender identity, even if it is different that what is stated on their ID, is setting themselves up for trouble... for those of us in states that have yet to legally protect transgender people from discrimination, the EEOC still views gender identity discrimination as sex discrimination, even almost one year into the Trump era.
(FYI I'm not a lawyer)
My personal stance is that it is not the government's job to try and regulate people's gender identity or gender expression, and that anyone who justifies the use of a gender marker on government documentation to try and dictate a person's gender expression (including employers/managers) is giving the government permission to interfere in people's lives in ways that could be very dangerous. Although many conservative people may be unlikely to agree with transgender rights, they are often skeptical of the government especially if they have libertarian tendencies... though I doubt it would be convincing in all situations such as yours, this would be the argument I would use to try and advocate for the ability to express myself according to my gender identity if I were ever faced with your situation.
