The more I think about this the more I agree with those who have said maybe the activist who complained was particularly thinking about girls who are starting to identify as nonbinary, genderfluid or outright transgender, and who could therefore be in denial about being girls. (Transboys, as they might call themselves.)
What a dreadful mess this is. Yesterday I came across this BBC documentary from a year ago: Transgender Kids -
Who Knows Best? vimeo.com/217950594. It is really excellent and very even-handed in its treatment of this whole agonising issue. As such, transactivists have done their best to get it banned.
There's a father in that programme who took a very hardline stance with his daughter. She spent six years (from age 6) denying that she was a girl until finally (and after I think some therapy from an old-fashioned watchful waiting advocate, rather than a counsellor recommending immediate gender affirmation, as she would be likely to get now) she started mixing with other girls who shared her 'tomboyish' outlook and interests. I suspect her parents had been trying to fit their square peg into a round hole and also had to change their views a bit after seeking help. He seemed very bothered about her having her hair cut short (not that short - a longish bob). Anyway, along the way, he simply said to her over and over again that she was a girl, no matter how much conflict it led to. His view was that she couldn't deny reality, and neither should anyone else. And now in her mid-teens she is OK with being a girl, and seems much happier.
It must be very hard to have a child with gender dysphoria. I can see that it may seem easier and safer to go along with the delusion and say 'Yes, of course you can be a boy!' They are so often told that if they don't their child will commit suicide. But in the long run surely it is better for everyone to try to get the child to accept the reality of the sex they were born into. Having irreversible hormone treatment and surgery should surely be a very last resort for only a very few adults - not children.