That was an obiter, not part of the judgement. Maya could no more use pronouns to harass colleagues than colleague could to harass her. So, for example, if she followed a trans colleague around shouting ‘he! He! He!’ that would be unlawful harassment, if she referred to him as ‘he’ in the normal course of a conversation then it would not be. At no point does the judgement require someone to use pronouns in a specific way. It did however make clear that not only were Maya’s GC beliefs protected, so was their expression.
On the other hand Lee vs Asher’s Baking Company Ltd set down cannot be obliged to manifest a belief you do not hold. In other words, you cannot be required to pretend someone has changed sex, by using opposite sex pronouns, when you do not believe that is possible.