This part:
the guidance mandates that where-ever such services are provided they must be restricted according to birth sex. The logic posits that in admitting some individuals of the “opposite” birth sex (e.g. trans people) the service would cease to be “single sex” and must therefore be open to all members of the opposite sex to avoid being discriminatory.
Meanwhile, however, the guidance asserts that trans individuals may additionally be excluded from the provisions designated for their birth sex. According to the judgement, the latter would be allowable in circumstances whereby the ‘gender reassignment process [had] given [the person] an appearance or attributes to which reasonable objection might be taken in the context of the [sex-specific] service being provided’.
In other words, according to the EHRC guidance, it is arbitrarily discriminatory, and therefore unlawful, to exclude some but not all individuals from services that misalign with their birth sex on the basis of gender.
However, it is conversely permissible (and not discriminatory) to exclude some (and not all) individuals from services that align with their birth sex, on the very same basis (of gender).
There is no sense to be made of these provisions other than that they seek to exclude people for simply being gender non-conforming.
The judgement is reasonable and makes sense if read in the way that Lord Sumption asserts (and in the way that the law has always been applied) - that it may be lawful to exclude trans women from some female spaces where this is a proportion means of achieving a legitimate aim. It makes no sense at all from a perspective that reads the judgement as mandating the exclusion of trans women from all female spaces in all circumstances.
The EHRC is like something out of an Orwellian novel.