People saying that Cass must be saying this because she has had death threats and been forced into it, or because she's madly in favour of transing kids are just barking. She has clearly stated her reasons, and while you may disagree with her reasons, there's no evidence of her being an ideologue or coerced into what she has said.
The is a very good point to be made. At the moment, we have two 'sides' yelling at each other - one saying that these drugs are dangerous and shouldn't be allowed anywhere near kids and the other saying that these drugs are lifesaving and totally necessary. Both sides can wheel out people who have taken them to support their view.
And we have a method which can help decide who is right - the clinical trial which has long been used to provide statistically valid evidence of efficacy or otherwise of drugs.
Will not doing the study prevent harm to children - unlikely. There are many, many people, internationally, happily giving these drugs to kids.
Will doing the study and finding statistically valid evidence of issues prevent harm to children - yes. The unethical internet doctors will probably still keep peddling their crap but it should certainly halt at least some of the evidence-based ones. And parents and carers can be pointed in the direction of some solid research to protect them from the unethical snake-oil salesmen.
People going on about the 'data linkage' study: Cass has already outlined why it would be crap data and easily dismissible. It certainly wouldn't be statistically valid data against puberty blockers in particular and it definitely wouldn't stop the people yelling that they are life-saving.