"It can be considered “injudicious” to express opinions about gender identity issues in casual office chats, employment judge Lesley Murphy said, adding that it was ill-advised because of how those views may be perceived by others."
But if it's "unwise" to talk about gender at work (and it might well be) doesn't that include claiming to be non-binary?
https://www.thetimes.com/article/0ad11f88-681b-4d3f-b612-c2620373f18d?shareToken=02e52f48d5b414b8e5514f1eedcf740b