A person might claim that they were discriminated against if they were rejected for a role that involved safeguarding, such as a residential camp leader, because they believed that select groups of males and females should be allowed to sleep in each others' dorms, or play contact sport on the opposite-sex team.
Just believing that wouldn't be problem. It's refusing to give women the choice of female-only provision, and lying to them or concealing the truth about the presence of males.
There are separate things at play here - women can claim effective sex discrimination by failure to provide female-specific provision, forcing providers to provide it. If an employee then refuses to provide that provision, which their employer is asking for, then at that point we find out if they can claim constructive dismissal due to being compelled to provide female-only services, when that's against their belief.
We'd want to be looking at cases like people refusing to be provide services because of their religion. Doctors not wanting to perform abortions, chefs not wanting to work with meat, sort of thing.
People not wanting to provide female-specific provision because of their beliefs is like that. How far can they refuse to provide service, and how much leeway can we give them.
As I understand it, the general answer is that individuals can't be compelled to do something against their conscience personally, but they can't make the organisation comply. A doctor may not have to carry out abortions, but they can't demand the whole organisation they're working in not carry any out, and clearly you couldn't have the entire staff refusing.
In these cases it's not just individuals doing personal conscientious objection, it's forced compliance organisation wide. That's what would make it fail the WORIADS test.