They inquired if he had a pre booked flight home:
>> Our medical team believe this injury may require long term care, so we would see if beneficial that you return to the UK for treatment, if you have a pre booked flight home please advise us on the date?
His response to that line was:
>> The medical team here have suggested that I will require physiotherapy once a week for 4 to 6 weeks. I have no return flight booked at present, as I intend to stay in Asia for some time yet. I did consider travelling home to have surgery in the UK, but the medical Service is excellent and I'm already scheduled in for the procedure on Monday.
The partial quote you took, "I intend to stay in Asia for some time yet", was his justification for not having a pre booked flight home, not an expression of his refusal to comply with their recommendations.
> He wanted to keep traveling and avoid the NHS.
You've also mistaken his desire to finish receiving treatment in Singapore as a desire to avoid the NHS. His desire was to receive the most immediate care possible and the surgery was intended to install a plate to stabilize his hand and ensure that it heals properly.
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.
The were asking him to transition his medical care from one hospital to another in another country on the other side of the globe. That by itself would introduce considerable delay in treatment as the new medical team would need to fully access his treatment up to that point and establish a new treatment plan. The surgery he was prescribed was to stabilize his injury to ensure it healed properly, delaying that treatment could potentially lead to improper healing.
As someone who popped a pulled tendon and had to wait 6 months (MURICA!) for an appointment with an orthopedist at which point my injury was healed (thankfully correctly), I can fully understand his desire to stay put and finish his treatment.