'in young people with gender dysphoria we are taking a normal surge in pubertal hormones and disrupting it.'
Why? What is the clinical rationale for inducing endocrine disturbance in a healthy child who is dissatisfied with being the sex that he or she is?
'That is why it is much less clear what the long-term impact of that intervention is, and why we need careful clinical trials.'
No, that does not explain why we need clinical trials. Cass has already correctly explained that to give puberty blockers to a child with 'gender dysphoria' is to disrupt the normal development of a healthy child. To present so clear a case for not experimenting on healthy children of normal pubertal age with drugs that disrupt their essential normal development, then to follow that by saying this is the reason we need to experiment on healthy children in a way that disrupts their essential normal development makes no sense at all.