It's right there in his e-mail. He was concerned:
"About potential waiting times on the NHS".
>They were asking him to fly for 20+ hours in a coach seat, considering his hand was unstable that seams unreasonable. It also increases the likelihood of additional injury as he travels.
IMHO if his hand is well enough to be discharged then the presumption is it's well enough to travel. Of course, he can provide evidence from his doctor to rebut that presumption. The insurance co asked for that but it's not clear he ever provided it.
>The were asking him to transition his medical care from one hospital to another in another country on the other side of the globe.
Which is the service he paid for. Travel insurance is to pay for emergency care until you are able to fly home. If he wants an "any hospital, for any treatment, in any country" policy those are sold too, but, naturally, are much more expensive than Bronze level travelers insurance.