I have no doubt that belief in transgenderism would be protected under the belief pc of the EA.
It would have to satisfy the five Grainger criteria:
(i) The belief must be genuinely held.
(ii) It must be a belief and not an opinion or viewpoint based on the present state of information available.
(iii) It must be a belief as to a weighty and substantial aspect of human life and behaviour.
(iv) It must attain a certain level of cogency, seriousness, cohesion and importance.
(v) It must be worthy of respect in a democratic society, be not incompatible with human dignity and not conflict with the fundamental rights of others.
Personally, I'd take issue with cogency and cohesion but still think it would sail through the tests with the right case.