You can not declare her views are not incompatible, because you do not know on what basis the service is contracted. If the MS Society's funding is entirely on the premise that the service operates a fully "inclusive" service, and it is perhaps bound by the strictures of parent organisations, which most services that make use of volunteers are, then I can see a scenario where anyone questioning gender ideology would give management palpitations
That's not correct. Management can have palpitations if they like, but they cannot refuse to employ someone who is GC, because they are GC. That's literally what the Forstater ruling says.GC beliefs are WORIADS and are covered by the protected characteristic of 'belief' in the Equality Act. You can ask your staff/volunteers to respect others' beliefs, but you can't refuse to employ them because of their beliefs. Just like a CofE school can't refuse to employ a Muslim teacher, same basis in law.
Yes, my organisation is, of course, bound by the Equality Act like any other. EA is covered extensively as part of volunteer training. The Equality Act refers to Protected Characteristics though, and for the most part "views" are not Protected Characteristics.
The belief that sex is binary, fixed and immutable is specifically included under the protected characteristic of belief. That's the law. For the most part beliefs are not protected under that characteristic, but that one is.
"Religion or Belief" certainly is, but even then, the law permits me to discriminate if your "beliefs" are fundamentally incompatible with the provision of my service, or would actually place me in breach of my contracted terms, or would present an intolerable safeguarding risk to my service users.
I can't see how a belief which has been tested in court and found to be WORIADS could be fundamentally incompatible with a legal service. As above, a Muslim is entitled to their belief, and you cannot discriminate against them for that belief. Nor would being a Muslim be in breach of terms of your service, or present an intolerable safeguarding risk. I think you'd be on very shaky ground, if you tried to argue that it was. The belief that sex is binary, fixed and immutable is protected by the Equality Act in the exact same way as a Muslim's beliefs are protected. You may need to check your understanding of the Equality Act with a lawyer, if you genuinely think you can discriminate again people for holding a legally protected belief.