As is the case with many anti-discrimination policies, often the actual result can be the opposite of what was intended.
Many employees are not comfortable with the accommodations for trans colleagues required of them by their employer (and by our current legal environment). Those employees don't really have a means to have their concerns addressed: it is either comply or quit/get fired. A way around that is to simply avoid hiring trans people.
That you do not understand those concerns does mean they are not understandable.