It does say in the article there was NO objection to showing it to her/another individual parent on school premises, but they refused to allow it to be shared any wider:
"“What the ICO and the judge are trying to suggest is that I as a parent may have had a right to see the lesson plans but that doesn’t mean it could be seen by the world at large,” she said. “I believe all state-funded school resources should be published, citable and open for public or regulatory scrutiny.”
Page said that she wanted to be able to share the material with bodies such as Ofsted or the Department for Education if she felt it raised safeguarding concerns.
School of Sexuality Education wrote to Hatcham College in November 2021 to say it was happy to show Page its slides in a controlled setting but the college did not pass on the message. Page said that she has not seen the full material because the only opportunity she was given was at a meeting when the head of the school’s trust offered to show it to her on a laptop. She said that she gave the laptop back after viewing only two of the slides because she wished to view the material with her daughter and husband, and have the opportunity to share it more widely."
This still seems fairly rubbish to me, and as she says, does not give an opportunity for it to be reviewed and critiqued by someone with safeguarding experience for example. I hope she does appeal and is successful!