We've come across the 'Bananarama' thing before - it's not what you say, it's the way that you say it [it should be the Bananarama AND Fun Boy Three..].
You have the right to express your WORIADS beliefs, but in a reasonable way - I agree, it would be wrong to walk up to a random trans IDing man in the street and shout at him out of the blue 'You're just a man in a dress!' even though he is just a man in a dress.
We saw in the Sandie Peggie case that there is a problem with this - there was no way, polite or impolite, intemperate or pleasant, that SP could express to DrU that she objected to him being in the women's changing room.
To him, that was inherently offensive.
The same could be said in this case - there was no way that KL could assert his disagreement with joining in the 'social transitioning' of a school student in a way that would not be considered unacceptable.
He may well have overstepped the limits, but the key point is: how does someone in his position assert his WORIAD beliefs without getting sacked?
The tribunal could rule that KL overstepped the limits, but it could still be useful if it ruled that a teacher is entitled to refuse to use wrong sex pronouns, and names other than those by which a student is registered.
Obviously, they should not be offensive in how they express their refusal, but if it was established that they were doing nothing wrong in so doing, teachers wouldn't have to be drawn into confrontations about it.
There's a matter of principle behind this case, not just how the individual handles their assertion of that principle.