I think it's very likely that the child will desist after puberty
Yup. If by 'desist' you mean 'die'. Because that is also likely.
Evidence suggests that four in five pre-pubertal children diagnosed with GID do not go on to experience the condition in adulthood.
Sorry, nope, that's been debunked here: www.huffingtonpost.com/brynn-tannehill/the-end-of-the-desistance_b_8903690.html
It's exactly that kind of crap that I'm trying to fight against. Because you are basically saying 'oh they will probably grow out of it, don't do anything'.
I think medical transition is a very poor outcome for anyone
Unfortunately the evidence on all respected long term research into the outcome on trans people (you know, the like 5 articles I linked that are all proper scientific research from all over the world) is that medical transition is a much better outcome.
You are of course entitled to have an opinion. But opinion does not outweigh fact.
And for the poor mum's dealing with trans children they need facts, outcomes and science. Not your incorrect opinions.