From the language used I think they’re in the US @ScrollingLeaves; & as the commenters suggest, companies will bend over backwards for trans employees. (Unless it suits them to argue that trans people are at risk of losing their jobs just for being trans [& that is why a disproportionate number of TW “do sex work”] of course.)
The ADA, of course, guarantees the lady who works as a courtesy clerk, protections under the law. No legal rights for women as a sex class in the US though.
Depending on where in the US they are, the individual complaining may not legally be allowed to use the women’s toilets. OSHA, being subject to institutional capture, merrily slides round that fact; cheerily bringing up the shameful misappropriation of Title IX by the trans lobby.
That disingenuous wail of “what can I dooooooo?” is frankly shameful. How “lucky” this individual has a supply of people ready & willing to support their ableism; & tell them that a perfectly reasonable response is to destroy the life of a woman who actually will (despite the ADA) struggle to find alternative employment. Ugh.
Imagine repeatedly & deliberately causing a woman with a developmental disability (& statistically, quite likely cardiac issues) such acute distress. The level of self-absorption required for such selfishness is staggering even to contemplate.