I'm often loath to compare my disdain of loon beliefs with religion, knowing that it isn't quite the same and religion gives some people (like my mum) solace and peace...It's a bit more nuanced than that because Religion is literally a belief so it fits into the legislation and you would be protected.
The problem with Sex is that it doesn't. Biological sex is not a belief, it is a material reality and no one should be forced pretend otherwise.
Men do not pass (Women can) so we are being expected to ignore what our eyes and senses tell us and lie.
I think the more accurate (or completely fact related) comparison is, this is a mental illness and we should not, in general be forced to believe their delusions.
If someone tells me that unicorns exist, or that they are really *insert famous dead person* incarnate, I'm calling bull.