From memory, the GRA only prohibits sharing the information that someone has a GRC if that information has been gained in an official capacity, which TRAs have routinely spun as it being against the law to ask if someone has a GRC.
It sounds very similar to the duty of patient confidentiality in the NHS which was explained to me with the following examples (although others might have been given a different interpretations):
Example: You are on the business of your NHS employer (any job, clinical or non-clinical) and walking down a hospital corridor you see someone in the distance who you recognise as a neighbour. You do not know the reason for him being there but the safest course of action is to assume that he is there as a patient and that you therefore owe him a duty of confidentiality. If you bump into his wife in the street it would be a breach of confidentiality if you volunteered, or confirmed when questioned, that you saw him on hospital premises.
However, if you were a visitor or patient yourself and saw your neighbour on the hospital corridor then you owe him no duty of confidentiality.
The first case would be equivalent to the confidentiality required under the GRA if you gained information about a GRC in an official capacity. In that case, the GRA would require you to refrain from referring to a "GRC woman" as a man (as per Lord Filkin) in order not to disclose your knowledge that they have a GRC. Nothing to do with "courtesy" or "avoiding causing offence" and everything to do with confidentiality.
The second case would be equivalent to, for example, seeing a selfie that someone had uploaded publicly on Twitter in which they are proudly brandishing their freshly-minted GRC. (As if that would ever happen! 
)
Everyone involved with the GRA imagined, or at least portrayed, transsexuals as shy, retiring creatures doing their utmost to be perceived as the opposite sex. Not as bearded bullies bragging publicly about their spanking-new protected status as gender-reassigned, legal-fiction females.
Whatever, the fact is that if knowledge of a GRC is not gained in an "official capacity" then there is no legal requirement under the GRA to avoid "misgendering" of any sort.
The GRA and GRCs refer to male and female, those "nonexistent" biological sexes according to Judge Tayler. If someone does not have a GRC then they are not covered by the GRC-related confidentiality requirements of the GRA. They are only protected by the Equality Act if they have a GRC or are intending to get one and "non-binary" is not an option.
So, I do not understand why the judge considered Gregor "non-binary" Murray and his They/Them pronoun preferences to be in any way relevant to Maya's case.
More relevant, I would have thought, is the fact that "being trans" is now a badge of pride and not something that most people seek to keep confidential. Also that at least some people with GRCs are publicly acknowledging their biological sex and asking that others do so.
The whole ruling is just . . . bizarre . . . like reading something out of Discworld!