I'm utterly aghast! Does Partridge Madeley have any qualifications for doling out this advice? Aside from minor celebrity and a long gone career as a chat show host.
https://archive.ph/gNrcX
https://www.telegraph.co.uk/family/parenting/dear-richard-autistic-teenage-cousin-wants-to-transition/
Has he been living under a rock? It's obvious he hasn't read Cass but did he even read the letter? The child is in care, probably with SWs enthusiastically waving the progress flag, parents too ill to look after her. None of that seems to register with him. He can't see the red flags. Isn't aware of how 'looked after' Children were massively over represented at the Tavistock. How, isolated from her family, she's more vulnerable to social contagion and a 'glitter' family prowling, ready to fill the void.
I agree that as a cousin the writer's influence may be limited. If he'd advised them to step back for the good of their own mental health, that would have been one thing, but that's not what he's done!