I think to get back to the core of the case, it is about deception. Not even whether someone claims they are trans or not.
But was someone decieved into being sexually intimate with someone becasue they genuinely believe that were the sex they said they were.
I thought the legal issue rested on this, as in other cases such as a woman who sued because she only had sex with a man because she thought they were going to be married. (He was lying) And a Palestinian man sued by a Jewish woman for deceiving her.
Isn't this why some trans groups have been so against having a law of sex by deception, as they dont think it is deception to say you are the sex you identify as, and for someone to argue that it is, is saying in legal terms that it is a deceit, ie you cant change sex.
And there have been cases in the US where men who feel they have been deceived by having sex with a trans woman who they accepted as biologically female, have argued that their violent response (ie attacking the trans woman) is a "natural" response, ie mitigating circumstances. (Some have suggested that this violent response by men maybe one of the reasons that trans women working as prostitutes have a right rate of being attacked, and in some instances murdered.)
So it isn't about whether someone genuinely thinks they are male or female, it is about how the person they are interacting with perceives what has happened.