Justice Swift's judgement was on the whole clear and accessible e.g.
35 ... the Claimants’ submission was that having provided a room for women, the 1992 Workplace Regulations do not prevent the employer adopting a policy that the room could be used by both women and trans women. Thus, the submission goes, regulation 20 requires no more than the provision of facilities and says nothing as to the manner in which those facilities should be used. I do not accept this submission. First, it places form over substance, disregarding the obvious purpose of regulations 20 –21 and 24 The obvious albeit unspoken premise of regulation 20 is the provision of private space for each sex for reasons of conventional decency.
37 It is clear from this that the objective of regulation 20 is that men and women should use conveniences in separate rooms, not together in the same room.
However, he also indulged in some regrettable asides and 'what if's, e.g.
61 I consider there would, in principle, be scope for a strong argument that a rule or practice that permitted trans women to use the “female” lavatory but required other biological men to use the male lavatory would comprise different but not less favourable treatment on grounds of sex. However, the circumstances of the case would be decisive. (For the purposes of the EA 2010 the lavatory would be mixed-sex, but for the purposes of the Claimants’ submission in this case it would still be labelled “women”.)
He was musing on whether a non-trans man would really be 'disadvantaged' if the segregated Men's toilet he was restricted to, unlike his putative transwoman colleague, was exactly the same as the Women's toilet, which is unlikely - men's and women's toilets tend to have different 'furniture', facilities etc.
Either way, Justice Swift also said that if transwomen were allowed use the 'Women's' toilet, it would then cease to be a women's toilet, and would become a mixed sex toilet,
5 One clear consequence of the conclusion reached in For Women Scotland was that if, for example, a service provider provided a service to be used both by women and transsexual women, that service would not be a single-sex service.
So his thinking-out-loud about this technicality was unfortunate, as it was seized on and misinterpreted by some commentators.
While safety is a very important reason for single-sex spaces, it is not the only one. Justice Swift asserted that separate toilet facilities for men and women are
35 for reasons of conventional decency and
28 "necessary for reasons of propriety”.