Second Guessing The Supreme Court

I've been struck by some of the trans activist language used in the decision of the Sandie Peggie employment tribunal which is peppered with references to 'sex assigned at birth', 'self-ID' and 'presenting as female'.
I think it's fair to ask where this language comes from - does the employment judge, Alexander Kemp, or his fellow panel members have any links to trans activism?
In my view it's not the job of a 1st tier employment tribunal to be second guessing the UK Supreme Court when it comes to the provision of single sex spaces including changing areas, women's sport, rest rooms etc.