There are other potential conflicts in the EA2010 e.g. religion and sexual orientation. The whole point is it is not a hierarchy the pc are equal/equitable.
The SC decided that sex, woman and man in the EA2010 meant biological sex rather than legal/certified sex. This affects and clarified the interpretation of the pcs of sex, equal pay comparator, sexual orientation, pregnancy and maternity.
It did not change the pc of gender reassignment and confirmed no one should be discriminated on the basis of GR. The GR pc has never entitled people to use SSS on the basis of self ID. Discrimination is not recruiting someone to a job, not providing a service they can access e.g 3rd spaces, Trans rape crisis centres etc.
It is the GRA that might (just might) have permitted people with a GRC which changed their legal/certified sex to use SSS based on their legal/certified sex rather than biological sex. The SC said no SSS are based on biological sex.
What ST, ED and TRAs have not understood is what the law actually says instead they believed Stonewall for decades and a lot of employers and service providers were to scared to say no.