I struggle with reading comprehensions? Let's break down your comment, shall we?
"The school isn't "promoting breast binding to girls"."
Yes. It is. I highly doubt schoolchildren are allowed to send out newsletters without some kind of teacher/school supervision. I remember when I worked on the student paper at sixth form there was a supervising teacher who checked the content and occasionally asked us to change it. If they don't have such a supervisor, that is in itself a safeguarding issue.
The school also provided the resources to create and send out the letter. Finally, they defended the newsletter after parents complained. So yes, given the newsletter contained a guide on how to breast bind, all of the above amounts to the school promoting it.
A newsletter prepared by pupils included an article on how to breast bind safely.
There is no way to breast bind safely anymore than there is a way to self-harm safely. It's not safe. End of. But beyond that, as a message to young girls who are just beginning to experience puberty, the idea that breasts should ever be bound (even if there were a way to do it safely) or mutilated is as regressive and dangerous as telling them they should be stuffing their bras and getting breast augmentations. No school would ever promote that so why are they promoting binding and mastectomies? Because one comes with a stamp of approval from Stonewall.
I'm not in favour of breast binding in any way but your post and the headline of that paper is dogwhistle alarmist rubbish.
Regardless of your view of breast binding, this post and The Times's headlines are not "dogwhistles" (dogwhistles of what? Would an article about a newsletter written by sixth formers to 11 year old pupils about how to be anorexic also be a "dog whistle"?) or "alarmist". As the many comments from current and prospective parents on this thread and on The Times's own comments section will attest.
I think my reading comprehension is just fine, thanks. Perhaps you should work on your own.