This is a classic case of: Do you have a facially neutral policy that may disparately impact certain groups, or do you create exemptions that although designed to help groups that are discriminated against may be seen as unfair to others who may be affected although in a less adverse manner? An analogous comparison would be back before same-sex marriage was universally recognized in the U.S. companies that allowed unmarried same-sex partners on their health insurance while requiring heterosexual couples to actually be married. Or, dealing with the transgender community, institutions that require everyone to use their legal name or when schools/the military have a policy not to update records to reflect a name change after leaving on the basis that they're "historical" documents; here the issue is that people go by a different name or change their names for many different reasons, but unlike most other cases where having a former name or name you prefer not to use floating around is merely a nuisance, with transgender people it usually effectively outs them in contexts where they'd rather not be.
(This is not the same as when for example a company explicitly prohibits same-sex partners on their insurance, an institution that allows cisgender people to specify a preferred name but not transgender people, or when they'll update the records due to name changes for other reasons but not for a gender change - in such cases that would be unquestioned discrimination.)
