"I was visiting family in London when the British supreme court handed down its unexpected ruling: under the Equality Act, sex was now considered “binary” in law, which meant transgender people could be banned from single-sex spaces of their gender identity. The Labour government, which had come into office promising us “dignity”, capitulated."
The Guardian are failing their readers by publishing this.
The government did not 'capitulate'. They must comply with the law, just as any other government must.
Sex has always been binary in law. Leaving aside trans issues, this was recently confirmed by a different judgement https://www.matrixlaw.co.uk/news/court-of-appeal-rules-that-nonbinary-gender-cannot-be-registered-in-the-uk/ and was not considered by the SC.
The SC considered a different question - whether a GRC can change somebody's sex for the purposes of the EA. However, it has always been the case that a single sex space could be segregated by sex, and it was confirmed in 2022 that somebody without a GRC does not have any right at all to use the facilities of the opposite sex.
Whether or not toilets should be mixed sex is a different question and the Guardian is free to campaign on that or any other issue, through normal democratic processes. However, my tip to them would be find lawyers who understand the law as it is, not as they would like it to be. It gets better results in court.