Rather off-topic for here, but the ruling was a very specific one. The Scottish government vowed to appoint men and women equally, but said that it would count trans people as their declared sex rather than their biological one. A women's charity said that was not compliant with equality legislation, and the court agreed.
Yes while the ruling was very narrow about what you mentioned, it has far wider implications of social space and structure.
One of the leading activist in this case was a lesbian. Her point was that in lesbian only spaces, why should those be open to men who have transitioned to declare themselves as woman. The ruling brings forth a lot of uncomfortable questions about what British press calls single sex spaces. While on participation of transgenders in women’s sports is more cut and dry there are other other areas where everything is grey.
I head for first time about a man who was convicted of raping two women and then in jail decided to identify his gender as a woman and was put in women’s jail as a reason. That sounds so ridiculous but I think it happened in Scotland.
On some of the more thoughtful discussions I watched, there was a question that if a trans-woman had an emergency appendicitis operation perform, will she (he) find herself in male ward or female ward.
Then I heard of a few cases in UK where people lost their jobs for identifying by sex rather than gender.
The biggest and simplest indictment of this whole gender vs biological sex is the gotcha question by the right (in USA and the west) asked of politician “who is a woman” or “ what is a woman”. The answer to that was clear till recently and now that question is like a hot potato.
The UK Supreme Court also pointed out that this legal definition of sex, doesn’t do away with protection against discrimination for transgenders under the equality law of 2010 and other law from 2004.
Declared or adopted gender vs biological sex when in conflict creates a lot of questions on how social and public places should be structured.